I'll disagree a bit with MaltLicker here, but only a little. And sorry for the word games that follow.
Consistency is determined by your brewing technique, not your brewing "methods". If you choose to not mash out and you are consistent with the timing and order you perform your technique, you will be consistent. Two brews with the same recipe and the same mash profile, one with, the other without a mashout will certainly produce different beers, most likely the one without a mashout will have a drier finish/ lower FG (held longer at enzymatic temps), the one with a mashout will likely have a higher OG and FG (better rinse and higher efficiency).
The purpose of mashing is to achieve the sugar profile in the wort that we wish to have to produce the beer we want to make.
Using a Mashout is one tool we can choose to either use or not use, awesome beers are brewed both ways. Necessary? No.
you are the brewer so it is your choice.
Fred