The amount of dialogue I can bear really varies a lot.
For example, I'm not shy about going on and on about my love of Homestuck, which is famous for having a higher word count than War and Peace, and features incredibly long, rambly conversations between characters, sometimes written with weird grammatical quirks like a character who T4LKS L1K3 TH1S 4LL TH3 T1M3 but I'll also frequently come across a Tapas comic, see all the text and go "...nah", even though there's far less than Homestuck would have, so I think I probably have a set of criteria more than a specific amount:
- Is the font and text size/formatting appropriate to make it comfortable to read that amount of text? Like does it feel like the amount of text on a page balances nicely with the number of pictures?
- Is what they're saying a compelling part of the narrative and action, or is it like video game filler dialogue I could skip through or skim read and still follow the plot?
- Even if it's not vital to understanding the plot, is what they're saying still so interesting and well-written and gives me such an enjoyable insight into the characters and their relationships that I'd read it anyway because it's just so fun, funny, smart or well-realised?
The thing that makes the dialogue in Homestuck so unskippable is that it really IS the comic. It's where you get all the meat (or candy?) of the characterisation and storytelling, plus a lot of the funniest jokes. The characters have really distinct voices, not just in terms of speech quirks, but their personalities come across very strongly, so you end up hooked on just seeing how different pairs or groups interact in different scenarios and seeing what the different dynamics bring out in them.
I always feel the same way about say, John Allison's comics (like Scary-go-Round, Bad Machinery etc.) he writes strong character voices and the characters say these interesting and funny things to the point he can write a scene of two women going to the estate agents to rent a house and make it a really funny, compelling comic where I'd never skip or skim a single bubble of dialogue.