I do not make safety holes, and it has not been an issue for me.  After butchering many a baby in the beginning, and successfully hatching a couple of severely deformed babies, I have only assisted with zipping ever since, especially if they have pipped at wrong end.  
If they are peeping, you have nothing to worry about. I typically drop my temp 2 degrees (99F at egg level when cooking, 97F when hatching). I keep my humidity at 75%. Do NOT open bator!
	
		
			
		
		
	
				
			If they are peeping, you have nothing to worry about. I typically drop my temp 2 degrees (99F at egg level when cooking, 97F when hatching). I keep my humidity at 75%. Do NOT open bator!
	




