Personally I stop around 50-60, I think anymore is a waste. I built a khajiit StamBlade and it had 108% but didn't seem to hit any harder than my other build focused more on weapon damage. I'd say if you are in PvE and you have 60% without thief mundus than invest more into weapon/spell damage/ recovery/Max stats or crit damage bonuses such as Shadow mundus and CP
In general you should have ~60% by default:
- 10% base rate
- 12% from cp passive
- 10% from light armour
- 10% from major prophecy
- ~17% from thief mundus
- (3% from minor prophecy if there is a sorc in your group)
If you use armour sets that have crit as part of their bonus like burning spellweave, aether, scathing mage or julianos it's not wasted. However, sets that focus on crit like mothers sorrow ar usually not as beneficial as increasing your other stats would be. Using a precise weapon is usually not the best idea unless you are in a group that has enough armour debuffs on the enemy to make sharpened useless.
If you are over 75% then I would say swap out that crit for base damage. There is such a thing as too much crit chance if your base damage suffers cause of it. Look at Infallible Aether vs Moondancer right now. Only difference with their 2-3-4p bonuses is IA has 3% spell crit as 2p and Moondancer has 967 Max magicka and at the moment Moondancer out parses IA, which is why everyone is grinding for moondancer gear. Similar fashion for PvE Stamina, I would recommend Redguard or Orc over Khajiit. Higher base dmg vs Super high crit chance.