There are a lot of good alternatives to a peep sight out there that have none of the potential drawbacks (improper rotation/alignment, can't see through in low light, some use rubber tubing that can break, loss of fps due to their weight on string, can move on string if not properly secured, most don't show if your torquing the bow, etc, etc, etc...). But even these alternatives are not absolutely necessary.

If one practiced to develope a repeatable anchor point with at least two to three references (V of release hand on lower jaw bone, nose contacting string, fletch in corner of the lip, etc) no peep type aid would be necessary. As stated above, they only serve to help establish a common anchor point... Best advise I can think of is to try different things and go with what gives you the most confidence...