Its not that i mind manga doing impossible stuff - it happens all the time - but - i dont want it 'utterly impossible' to the point of 'too dumb even for fiction' - like stopping time for the whole universe would be - who's she meant to be - the creator of the universe?
As for sakuya, like i said, id always assumed most who can stop time, are actualy just removing 'themselves' from it - so they can move etc instantly seeming and then 're-enter' the flow- that's a WHOLE lot more believable- even in a world with magic.
And the freezing time while talking to people and then walking off and nobody says anything?? It's not 'overthinking'. Its not like i mind the basic premis a schoolgirl can freeze time in some way. But you can do that well, or badly - I just wish it was self consistant and not full of obvious issues.
All that said- i still find it somewhat enjoyable and will keep reading :) Though I also didnt like the long haired girls attitude in part 2 - hope she isnt as shallow as she seems there.
You know, most of the time when the 'Time Stopping' trope is used, the user usually does stop the entire universe. Limited time stopping is actually the exception since it'll cause major issues like a part of the world being out of sync with the rest.
The walking off part is a problem, though. Maybe her power makes people automatically forget about her, amnesia-like?