noticingthemistake has it spot on. The techniques mentioned are very useful especially for recording vocals i.e. record 3 takes with all the settings in identical places (i.e. eq gain etc etc) and make a montage of the best bits of all 3 takes ! With a bit of careful editing you can even use the unused bits of the other takes to double track.

If you are using a half way decent computer package you can even fix tempo problems with out re-recording the track providing you have your drum kit miked up properly i.e. one drum is not bleeding into the mic of another.