Sgisela Thank you. You shared two interesting examples.
The first one is something I didn't get why the author made this way in the first place. Especially why are sharing a beam, are located in the same clef range, but constantly change the lines?!?
At the first glance, it looks is like a brain teaser, or training material for music reading. Or the author wanted simply to have some fun looking at the student's faces when they see it. 🤣
Looking some minutes to it, it seems this a situation where both hands overlap at the keyboard? Like the right hand sits very flat on the keyboard and the LH does this stride piano style up and down, but on the upper part it overlaps with RH and is used to play a quickly repeated chord? (I see some 16th gaps).😵
About the lower example, in the first glance, there are lot of ledgers. But having both on bass clef only, one can easily see there is no overlap in both note ranges. And the ledgered notes are always the same. This means it is only 1 small mental step used for the entire lower line - which even a beginner like me can handle (except for the 6 flats). I agree on this example I would not use a 8vb notation to get rid of some ledgers.
Speaking about mental steps:
Sgisela I think this is less confusing than thinking about transposing the chords down an octave, which is an additional mental step.
I think an octave shift isn't a big mental step. I think, it is a bit smaller than changing to another clef. IMO, sheet music should be optimized to avoid additional mental steps. If you can avoid a clef change, avoid it. If you can avoid 8va, avoid it. If you can avoid ledger lines, avoid them. But you can't avoid all of those, so a compromise must be found.
It is even possible to apply a metric like:
8va/vb=50 penalty points.
clef change=60 penalty points. (maybe 50, if it is located after a long rest / long duration note)
1 ledger line= 1 penalty points
2 ledger lines= 3 penalty points
3 ledger lines= 9 penalty points
4 ledger lines= 16 penalty points
5 ledger lines= 25 penalty points
...............................(penalty points = ledger lines2)
If you look at an example like those 3 bars from the Keith Jarret Transcription (WieWaldi ) I think doing the octave shift once is a tiny mental step compared to facing a lot of ledger lines for many notes. (There are more bars to come with that note range)
