When using FAST Forward, how important is it for the treatment to be delivered Monday through Friday in one week as opposed to spanning a weekend?  

Presumably unimportant. From the protocol: "13. TREATMENT SCHEDULING AND GAPSTreatment can start on any day of the week.A gap of up to 3 days is acceptable in the event of machine service or breakdown. This is preferable to transferring the patient to a machine on which daily verification imaging ...