This was what promptly led me to turning off Jetbrains AI assistant: the multiline completion was incredibly distracting to my chain of thought, particularly when it would suggest things that looked right but weren't. Stopping and parsing the suggestion to realize if it was right or wrong would completely kill my flow.
The inline suggestions feel like that annoying person who always interrupts you with what they think you were going to finish with but rarely ever gets it right.
With VS Code and Augment (company won't allow any other AI, and I'm not particularly inclined to push - but it did just switch to o4, IIRC), the main benefit is that if I'm fiddling / debugging some code, and need to add some debug statements, it can almost always expand that line successfully for me, following our idiom for debugging - which saves me a few seconds. And it will often suggest the same debugging statement, even if it's been 3 weeks and in a different git branch where I las coded that debugging statement.
My main annoyance? If I'm in that same function, it still remembers the debugging / temporary hack I tried 3 months ago and haven't done since and will suggest it. And heck, even if I then move to a different part of the file or even a different file, it will still suggest that same hack at times, even though I used it exactly once and have not since.
Once you accept something, it needs some kind of temporal feedback mechanism to timeout even accepted solutions over time, so it doesn't keep repeating stuff you gave up on 3 months ago.
Our codebase is very different from 98% of the coding stuff you'll find online, so anything more than a couple of obvious suggestions are complete lunacy, even though they've trained it on our codebase.
Why not use a snippet utility. In every editor I've used, you can have programmable snippets. After it generates the text, you can then skip to the relevant places and even generate new text based on previous entries. Also macros for repetitive edits.