Joshua’s answer brings the point home.
a) This is an ‘it depends’ situation. Since the condition of your clients is not available, it’s hard to say if 3 days-in-a row bursts are a great idea.
b) High intensity training can stress the body a lot! An extra rest day (or 2) can allow the body enough time to recover.
Kepp in mind that your clients ‘may feel O.K.’ the first time they do these bursts but…can they do it on a regular basis?
Good points to consider.