Leveling is a complicated affair: there are four different mechanics that provide XP to people and seven different places where XP can be spent (level and each stat).

1 - The baseline "skillless" XP varies between 3 and 6 points of XP earned during sleep, based on the variety of activities you performed during the day. For modern-day people, you can consider an average of 4.25XP per day or 1550XP per year.

This XP is added to the "general XP" pool.

2 - The skill earning XP. This is earned individually per stat, per day. For each stat, each use of the skill generates XP based on the difficulty of the action, which is either the skill level divided by 2 (for non-combat actions), the number of resources spent in the skill up to the skill level, the skill check (example: Mana Sight gives XP equal to the skill you're seeing), or the skill level (for skills used in hostile environments). You can only earn XP in excess of previously earned XP for that stat.

Example: Perception. You Mana Sight a level 6 skill being used, you earn 6XP. You then see a level 22 skill being used, you earn 16XP (22-6). You then perform an unrelated Perception skill 35 action in combat, you earn a final 13XP (35-22). This resets upon sleep.

This XP is added twice: to the "general XP" pool, and to the dedicated XP pool for the stat (which can lead to an automatic leveling of the stat).

3 - The Kill XP. This is earned when killing any system-changed entity. This is equal to 500XP+25XP per skill, times the level.

This XP is divided among all people involved in the killing, based on "contribution" (which is extremely nebulous) and added to the "general XP" pool. For the four, it is evenly divided among any of the four presents, with an extra share being the "global XP pool" that can be spent by Moore on any of them, at any future time.

Examples: Captain Devereaux, a level 7 human, is worth 3500XP (7x500). Elena Worchester, a level 8 water shaper with a single skill would be 4200XP (8x525). A Level 12 Peak Unnatural Amphex is worth 6900XP (12x575).

There are diminishing returns per day that triggers whenever the author says it's enough XP for today, dammit. It has never been used, but I reserve author fiat, just in case (it's not under 5k per person, because I do have a 5k day somewhere).

Gruesome fact: During the Battle of the Kootenai Gap, over ~800XP of the 3000XP earned came from... Tribesmen killing Montana soldiers. Because Laura was using her Falter which affected everyone... and thus was contributing to those kills (and yes, they shared XP with the enemy troops. But if no one knows, what's the harm?).

4 - Defeat XP. This is earned when a hostile system-changed enemy flees or concedes the fight. This is equal to its current general XP pool or 100XP times the level, whichever is smaller. The XP is lost from the hostile's XP pool and then divided using the same rules as #3 above. It can happen for a given entity only once per sidereal year. Gaining defeat XP does not prevent you from gaining kill XP before the year.

Now, consider a few diverse people from the current Changed World:

Albus - This ordinary person goes through life in ordinary circumstances, earning its 1550XP per year of baseline, and that's it.

Bertram - This unspecialized, but skill-using person has a single 0-multiplier skill, obtained at age 30, whose cap is usually his effective level, ground every couple days in non-combat circumstances, for an additional 750-1000XP per year.

Crethon - This guard or bounty hunter spent times in the wilds, fighting occasionally a few low-level Changed, earning an additional 2000XP/year of kill XP, or 3500XP per year, from his 20s until the day he dies (rather than the day he retires).

Devonia - This sorceress has a single 2x skill whose cap allows a much higher grinding, for 5-6K XP per year from age 35 on.

Evander - This veteran of the Unification Wars has enlisted at 18, and seen regular combat; each battle he's survived has yielded 2500XP on average, and he's been involved in six-seven battles per year. That's 17000XP/year, people (until his death, not retirement).

Fiona - Someone with a real build, an advanced specialization she got by 18 because she was power-leveled when young (at an extra 3000XP/year - some minor contribution to safe kills by a real team), and now has six skills on six different stats, 3 of which (x1, x2, x3) are grindable every day. And she's a veteran of the RPG Apocalypse as it should have been, by the virtue of (censored, censored, censored, please desist), going into dangerous areas to clear Changed predators every month. She gets ~100XP/day of grind early on, but that goes to 200 "soon" and an extra ~8k/month of kill XP (plus use of all skills in those days when her team finds a Changed to fight). For a grand total of 140K XP to 170K per year.

And finally...

Garrosh the Grinder - Killing monsters, that's a job. 5 days a week, with a 4-week vacation, that's how we get our XP since I was 18. See and weep, boy-o (4K XP plus full skill use every workday, ~1M XP per year).

Here's the system progression for those seven people, assuming they don't invest at all in stats (and let them grow "normally" by skill use).

Level Albus Bertram Crethon Devonia Evander Fiona Garrosh (total XP needed) Age (rounded) (1000) 1 16 16 16 16 16 16 16 (2000) 2 17 17 17 17 17 16 16 (4000) 3 18 18 18 18 18 16 17 (7000) 4 20 20 20 20 18 16 18 (12,000) 5 23 23 22 23 18 17 18 (20,000) 6 28 28 24 28 19 17 19 (33,000) 7 37 35 28 36 19 18 19 (54,000) 8 50 44 34 39 20 18 19 (88,000) 9 72 59 46 44 22 19 19 (143,000) 10 108 80 59 51 25 20 19 (232,000) 11 114 84 62 30 20 19 (376,000) 12 80 38 21 20 (609,000) 13 107 52 23 20 (986,000) 14 73 25 20 (1.60 M) 15 107 29 20 (2.58 M) 16 35 21 (4.18 M) 17 44 22 (6.76 M)18 59 24 (10.94 M)19 83 28 (17.71 M) 20 35 (28.65 M) 21 45 (46.37 M) 22 62 (75.02 M) 23 89 (121.39 M) 24 In the end, everyone dies of old age... (120 years cap)

Note that, the average person typically "displays" a level under the one which they qualify for (sometimes two, sometimes none). Save those Fiona/Garrosh?

Just in case you're wondering:

Albus = random people from Valetta

Bertram = Dominik Piturca, the caravan master (with an awesomely preserved AC-DC teeshirt)

Crethon = Piturca's bodyguard

Devonia = Billy-Jo Weirky, the Flaming Hand sorcerer (or maybe Elena Worchester, who doesn't grind every day, but has a higher skill cap and has seen battles for XP instead...)

Evander = Sergeant Mord / Captain Devereaux

Fiona = Johanna's Daugh... oops, I said nothing! Forget this!

(I'm kidding, of course. I'm pretty sure the situation will look very different by the time they can take some time to have kids, and who knows what Moore will be able to do. But that's close to our four's potential career path... and it tells you they'll probably reach level 11-12 by the end of the trilogy, given they will spend stat XP)

Garrosh the Insane = actually, he was killed in his mid-twenties because there weren't enough mobs left, and he'd started killing people for XP instead.