General spacing issue

It's a little more complicated than that. We do take the entire line into consideration, but not until after also calculating a minimum width for each measure. And that is influenced by ledger lines, accidentals, dot, etc. See #299741: Inconsistent spacing of same-duration notes. There is some work going on to improve this some day, but meanwhile, do try out some of the partial workarounds that are suggested there, to reduce the need for manual adjustment. In particular, a small value for spacing and minimum note distance, then adding breaks manually, makes it so you only need to fiddle with stretch a little (and adjustments to specific notes should almost never be needed in any case).