Personally I think there is a time and a place for SLR as an exercise - I find it a very useful technique (with progressions of eccentric; active assist etc) to restore post-op or painful quadriceps inhibition when the patient is NWB or even PWB.

However as soon as the patient can complete it without pain and with activation patterns similar to that of the contralateral leg the exercise should be discarded as it is mostly a non-functional exercise (with the exception being transfers in/out of bed/cars etc). The same goes for inner range quads post-op and post-injury - regain the lost recruitment patterns and move on immediately.