Yes, even after only one 50-90 my 6s need a dose of 15+v to get back to 100%. But with solar doing maybe 80-95s it is easy to get back to 100. Doing a few 50-90s in a row means a lot of work on "recovery" once back home on shore power. So it seems that going deep makes a big difference.
OTOH before he got solar, smk claimed to be taking his 6s down below 50% and his 6s still work. Hard to tell what the deal is there, since smk also does not like to monitor things. Of course with 6000w of solar, he could have only 3 AH remaining capacity and not even notice. :)