I help if they have taken too long to zip...if they pip, and more then 12 hrs has gone by, and nothing more, i will attempt to help. Sometimes at that point, it's already too late.
I will pride myself in this last hatch, I help quite a few that ended up shrink wrapped due to them taking too long to get out.
Also, there were 4 eggs that I just assumed we're dead, due to them not even pipping....well, my fiance wanted to gently crack them open just to see what happened...and on day 23, one of those 4 as soon as we gently tapped the egg, I heard chirping!!!! the egg shell seemed VERY hard, and he couldn't pip. He was born VERY big and healthy
the birds are like my babies...and if I can help them stay alive...I will do what I can.
But, I deff let them battle it out for the first 8-10 hrs alone...(of course biting my nails the whole time, hehe)
good luck. it's a personal choice. everyone will have their own opinion. ... this is just mine. and all the ones I've helped have been amazing babies