In one direction, you don't want to overwhelm a potential editor, so you give small chunks; in the other, you want help with the larger issues of a story that by their very nature require large portions of the story, if not all of it, at once.
It's a tough call, really, and even in a critique group designed to handle entire novels, as critters "RFDR" is, you get one, maybe two people out of thousands who will step up to take it on. (Critters is a SF/F/H critique group that mostly handles short stories; "RFDR" is "Request For Dedicated Readers" - or somebody who will commit to seeing an entire novel through.)
For myself, well, I try to make myself the "other editor" for as much as I can, simply by leaving the story alone for a while to get some distance. Since I write SF, mostly, when I need an actual other person, I'll turn to critters. My boyfriend tries, but he can't point out exactly what's wrong, just that it isn't quite right. Helpful, but not quite what I'm looking for. I'm still working on him ;-)
In conclusion: You may find it useful to find a large(r) circle of readers. And/or find people who say `I like reading books but I couldn't proof read'. They often gloss over typos and bloopers without noticing but they will be quick to tell you if something is weak or does not add up. Benjamin F Jones [ Parent ]