'Schedule by Zapier' allows you to trigger a zap once per week, but if you want to do it twice, or even more often per week, you can achieve that by creating a zap that triggers daily and adding a filter step.
When setting up a zap with a "Schedule by Zapier->Daily" trigger, one of the returned fields is "pretty_day_of_week".
You can use this field to then build a trigger so the zap only continues on the days of the week you want it to.