Auto-translated
Regarding my experiment: I did it without a scanner, simply in single-player mode. I took Ingvar and immediately wrote down the "add_exp" result. The repetition occurred on the 6th attempt (for each attempt, I started a new game), and then I conducted attempts on a saved game, and the same skills always appeared in the same upgrade scenarios; I hadn't noticed this pattern before.
Regarding making all skills basic: we have the following situation (if we are offered skills from the same skill tree): let's say there are 8 skills in the tree, so the total number of options offered to us will be a combination of 2 out of 8, which equals 28 options. If we need a specific skill, then 7 options are suitable, which gives a 25% chance (if we choose a less useful skill, then for the remaining 7 skills, the chance is 28.5%, and for 6 skills, it's 33.3%) of getting the desired skill at that level. Currently, the chance of getting the desired basic skill is 66%, and for improved skills, it's clear: if there is 1 branch, then it's 100%, if 2, then 50%, and so on. For now, the calculations are only for 1 skill tree and only for one level, and they are not very useful. Later, I will try to provide more practical calculations (immediately for a pair of skill trees and considering several levels in a row).
At the moment, it seems that the advantage of the standard system is that it is less random compared to the proposed one, and the advantage of the proposed system is that there is a chance to get the desired skill, even if the skill tree is at a начальный level, and in general, there is a chance to fill the skill tree only with the desired skills. Well, the disadvantages obviously follow from the advantages.