PNF protocol for differing sessions.

For sure I’d use the ham stretches after. I usually secure the leg with a slight bend in it and have the athlete slowly straighten the leg before pushing back.
The number of reps is flexible, depending on the amount of force the particular athlete feels comfortable delivering on rep one. Less force means tighter hams and requires more reps, starting with very easy resistance and observing the athlete’s gradual increase in force, rep after rep, till he/she reaches or at least approaches their normal. I’d cap it at 10 reps, and, if you haven’t got full range by then, leave it to another day.