There's nothing to feel bad about
plus we all have lives too so we understand it comes first
All being on the team asks is for one graphic a week or two to be made over the course of two weeks depending on how you want to look at it. Sometimes life gets in the way/keeps us busy so we may only make one graphic for that round which is ok too (we just don't want that to be too regular an occurrence). If you wanted you could always try make something in that time frame to see how you go as it may give you more of an idea on the time needed to be on the team