I was surprised the default status effect duration (that isn't lingering) is three turns, since this means you always know when it ends and can base your actions around that in an OOC fashion, and most importantly it needs to be tracked with even more recharge tokens.

So I looked at the dice. 'Hmm, fortune dice have 1 in 3 chance of giving a success...'

So, it should come out to the same end result if you just roll a fortune die for each effect on you, and it ends if you get a success. Then you just need to remember that you are On Fire and Blinded, not that you will stop being blinded in two turns, but the fire will last for another round after that.

I'm ok with the fixed durations... games have had those for years.

If you want to go random then rolling a 1/3 every turn isn't bad as long as you roll at the end of the turn. Over half the time the durations will be shorter than the fixed one 1 or 2 turns, 30% of the time the duration will be longer. I haven't studied them all, but that might be mean. We've had players in our 4E games who took 7-8 rolls to make a save at 10+ on a d20. Thats easier than 1 in 3!