In the past, arbitrary post per page values could be set. This allowed choosing values whereby a grid of any configuration could be filled.
Now we are forced to counts ending in either 0 or 5, which won't be optimal for all window sizes.
Moreover, the pools page has a different column count than the posts page due to the lack of the sidebar there, yet it is also impacted by the same posts per page limit.
Which is why I suggest simply changing the function to a "rows per page" limit, which would fill the columns regardless of the formatting.

New profiles are ugly btw.

I agree that the default post-page should be filled according to row/column sizes

Being able to set the post per page dynamically to fill a certain number of rows would actually be nice. It would probably be doable with a user-script currently (it would have to calculate how many posts can fit per row, multiply that by the requested number of rows, then add &limit=(the result) to the search)