Moronic Mondays - What fitness questions do you have?

For assistance work is it better to

• run the same exercises each week for multiple cycles
• run the same exercises for one cycle and switch it up the next one
• choose new assistance work each week

Bonus question
Should you run the same push/pull/leg assistance exercises every workout or one set for each day?

I want to run the 531 beginner program from the wiki but it is a bit unclear about that. They just say to not overthink it but I would like to do it right.