Nah that's definitely a personal choice thing. On the one hand, it can speed up production and help keep things "on model" when working with a team... but on the other it limits how expressive faces can be. I'd never do it myself; I just enjoy really getting in there with the subtleties of expressions or going off-model for comedic effect too much.
There's always gonna be inconsistency, especially in early pages, but so long as characters remain recognisable, readers seriously don't tend to even notice.
In the first 9 pages of my comic, Urien goes from looking like 19 year old Leonardo DiCaprio...
To looking like Miles Edgeworth.
The readers didn't care though, fortunately! Nobody has ever commented on it! 
The way I see it, it's like sitcoms. Have you ever watched a few seasons of a sitcom and then gone back and watched the first episode and everyone's a bit "off" because the actors haven't settled into their characters yet and the writers aren't used to writing them? Like how Rosa doesn't really have her distinctive gruff voice yet in the first episode of Brooklyn 99. Drawing comics is a bit like a performance. No matter how many prep sketches I draw, I never really "know" a character until I've "performed" them in a few pages; that's when they start to really develop their bodylanguage and facial expressions. It's the same with just... the overall style of the comic. The first few pages of Errant it looks almost like an indie slice of life, and it settles into the art style properly when the action elements come in and the style shifts bolder and more like a shounen manga and it pretty much stays there, because that's where I found my "voice" for this comic.
If it was a print comic and I was really bothered about consistency, I'd go back and tweak those early pages later... but I think there's a certain charm in that raw quality webcomics have where you see the development happening.