Best work patter part time

[FLOWER1982]

I’m Trying to work out what would be the best working pattern for a job I’m going for. It’s 20 hours. Would you do

a. 4 x 5 hour days so can do all school pick ups YABU
b. 3 x 7 hour days (roughly) YANBU

My mum does pick up one day and I can work flexibly so can do 8-3 one day and 8-4, and 9-5, so would only need asc one day.

not sure whether to do 3 normal days with 2 days off or spread over 4 days. Help

I do 22.2 hours (3 full days) spread flexibly over 4 school days. It works really, really well. I don't have to worry when an after school club is cancelled, I can always do swimming lessons etc after school and get homework done without rushing it at dinner time. And I still have one day off a week to do whatever else needs doing.
Plus, I quite like being in work over four days as it feels like I don't miss out on much there either as I'm only not present one day a week instead of two so doesn't take as long to catch up.