not always a 100% mind I don't think but its still a higher percentage of piece of mind, if cutting correctly and not cutting veins and membranes the baby will come out in its own time, it still needs to leave the membrane, if born without a egg tooth however it wont make it. in my experience most my babies from this season where born with egg tooth but the shell was tough as bricks due to a lack of water in the bottom of the container towards the end of incubation. I cut the eggs at full term 55-60days each clutch of babies did not slit the membrane till day 61 and day 67 even though the egg was opened earlier. however any baby that did not make it died off before and during the week before pipping the eggs, apart from 1 poor lil darling which suffocated in the egg not being able to get out of the membrane due to missing an egg tooth. all the rest are strong and healthy nothing wrong with them at all, even my 2 sets of twins are going well, most of the 1st clutch have eaten there first meals, onto there second shed and up to there 2nd feed. my 1st clutch are all starting go into shed mode.