Do you run the water while soaping up in the shower?

We've got a shower massage type thing with multiple settings that include a cutoff, but I never use it because we also have this water conditioner can before the shower massage that I'm pretty sure would just explode if it had to hold back our water pressure. Wife likes the conditioner bc she claims it helps with the itchy. I'm sure we could save some water if we used the cutoff, but it's not like we spend hours in there anyway.