If I'm going to try and do them, I'll usually look at the entire list and see if it's doable by my standards, and if it is then I charge ahead.
Unfortunately the only one I've reached 100% in is Blazblue: Calamity Trigger with about 3 or 4 other games that are in the 80-90% range.
It's always that ONE trophy that keeps me from finishing >[
Like Bayonetta, I have it at 94% or something, and the one I'm missing is finding all the witches resting places. So in order for me to find them all, I'd have to go and do all the ones I've already done all over again just to make sure they're done.
Too much to fuss with.