There is never a guarantee that the leak will be found.
I went out to one job like that, and asked if anyone showered with the slider door open.
"Oh no, my husband doesn't do that."
Finally after checking everything else, I cut drywall downstairs.
A year later I went back to install a new toilet. I asked about the shower, seeing the drywall was all repaired and painted.
"Oh yes, we figured my husband was showering with the slider open. He closes it now."
Don't feel too bad. You weren't the one getting things wet.