Forgive me my English
Your English is much better than my Russian.
Below I've pasted some settings from CW2 that deal with experience. As I mentioned before, most if not all of the models in CW2 described as "conscript" also have a TrainUpg value specified. There's a 7% chance per turn for that upgrade to to kick in, regardless of the model's experience level. Also, there's a chance per turn for a unit to gain experience and levels even if it's doing nothing. The maximum number of levels that can be achieved by models this way is 2, but you can set it higher or lower (see below).
As far as the realism aspect, I'll leave that discussion alone.
expMaxLevel = 1000
expProgCoeff = 100 // Prog Rate overall modifier in %
expXpGainCoeff = 100 // Xp gain overall modifier in %
expXpGainCoeffLeaderKill = 10 // Leaders get 10% of their subordinate SU xp gain
expXpGainCoeffLeaderDie = 5 // Leaders lose 5% of their subordinate SU xp worth loss
expXPGainWhenHittingH = 50 // this value of hundredth of xp when hitting an enemy
expMinLevelTrain = 1 // min level before we can Level Train
expChancePerXPLevelTrain = 7 // % chance per turn per level to switch to TrainUpg (if level expMinLevelTrain or more)
expXPLevelUpgRetainPerc = 10 // % xp kept when TrainUpg/TechUpg
expReplChanceSpendTechUpg = 50 // chance to spend a rpl when TechUpg
expAutoGainXPChance = 75 // % chance per turn to gain 1 xp
expAutoGainXPMaxLevel = 2 // max level that can be reached with autogain
expGainPtsOffFire = 50 // gain in hundredth of points to a given stat. Rounding to 1 starts at 0.50
expGainPtsDefFire = 50
expGainPtsInit = 25
expGainPtsRange = 10 // VGN is 0
expGainPtsROF = 10 // means first bonus is at level 11
expGainPtsDisc = 35
expGainPtsAslt = 65
expGainPtsPolice = 100
expGainPtsPatrol = 100
expGainPtsEvade = 100
expGainPtsCoh = 500
expGainPtsDetect = 7
expGainPtsHide = 7
expGainPtsAirRec = 50
expGainPtsAirCbt = 100
expGainPtsAirBmb = 100