"Limit all lines to a maximum of 79 characters"

[snippsat]

90'ish Beyond PEP 8.
Black use defaults to 88 characters.
I feel like 90'ish is okay for almost all i do,in very rare cases over 100 if it make no sense to split it up.

Also some wise advice in Black:

You can also increase it, but remember that people with sight disabilities find it harder to work with line lengths exceeding 100 characters.
It also adversely affects side-by-side diff review on typical screen resolutions.
Long lines also make it harder to present code neatly in documentation or talk slides