While it's possible to cheat, it's much more fun to test the boundaries to see if it's possible to finish the game without turning evil.
If I were to speedrun this, that's where I'd focus my attention.
So without further ado, let's overanalyse this idle game!
Basics:
The skills of Concentration and Meditation assist eachother. Creating a kind of multiplicative effect that boosts XP gain per daily tick. In the interests of efficiency it's important to level each as equally as possible. (As squares have a higher area/perimeter ratio than rectangles.)
Obviously increasing Max XP level is the most important objective of all. The question of when to press for boosting versus life extending is still an open problem.
I have, however, worked out an estimation for when to switch from increasing Concentration and Meditation into improving other skills. I anticipate that taking Max XP into consideration may add extra complexity in the decision making process. But that's a discussion for another time.
Early Analysis:
All skills have a starting XP requirement (baseData.maxXP) value of 100. You can work out the amount of XP needed to level up from level n to level n+1 with the equation: 100*(n+1)*1.01^n
The XP boost from Concentration and Meditation takes for from of:(1+(0.01*c))*(1+(0.01*m)), where c and m are the respective Concentration and Meditation levels in the current run.
These equations combine in such a way that it's possible to observe higher levels becoming less and less effective; owing to how much more XP (and days taken) are required for any increased boost.
The data:
So I composed a spreadsheet to calculate the best timing for most boost, but least wasted days ticking over XP gains. The results are as follows. Levels are calculated in lots of 10.
If the target for your 3rd skill is between level 10 to 50, levelling Concentration and Meditation to 10 is best.
3rd skill target 60 to 70; C&M level of 20. Target 80; C&M 30.
90 to 100; 40. 150; 80. 200; 120. 300; 200. 400; 280. 500; 360.
600; 440. 700; 530. 800; 620. 900; 700. 1000; 790.
1200; 970. 1400; 1160. 1600; 1340. 1800; 1530. 2000; 1720.