I use a needle to get the cap off very gently the day after they are above ground if it wont fall off from itself. I'm sure it makes more harm than good if the leaves can't get light as soon as possible and the seedling can stand up normally.
Blue and red certainly would gain from it if they still look like that, it is very obvious they are still looking for light so help the leaves fold out. As for the others don't give up on them but at least try to help them. I had one HK that didn't come up normally and when i brushed some coco off the top it was trapped in the seed cap as well. I removed it gently with a needle and carefully helped the leaves open up a little bit and it took off fine.
I hope yours make it man

Puffzter