mashle
the comparisn isn't entirely fair, since the first few episodes of mashle are entirely comedic, while hell's paradise is serious throughout the entire anime. but i do agree with OP's point that mashle handled timing far better. given how good the first couple of episodes are, i thought the rest will be as good.
but as the episodes aired it became clear that mashle only mastered comedy - nothing else is on the same level as the comedy. the fights are okay, but i only enjoyed them for the comedy. (in my very humble opinion) the flashbacks are atrocious, all of them being easily worse than hell's paradise ep1, and btw did you notice every sentence in this paragraph ends with comedy. comedy.
hell's paradise
i read the first post before watching the first episode, so i was expecting the pacing to be really really bad. but when i watched it and it's... fine? it's not the best but it's fine. it's the best they could've done while following the manga that closely.
pacing did get better because there are less flashbacks, but sometimes you'll get really awkward pacing, and sometimes you'll get scenes with good pacing that's completely ruined by the production issues. though there are a few scenes that are done quite well despite everything else literally falling apart.
in hindsight, the first episode's issues is probably related to those production issues - they probably weren't given enough time to make big changes to the script, so they had to follow the manga closely.