I used saw palmetto for 4 weeks after a prostate biopsy, I found it irritated or stimulated the prostate. At that time this was a good thing as it helped flush out the blood after the biopsy.
If the problem in the prostate is congestion or something similar then using saw palmetto to flush it out could be of benefit.
I now only take stinging nettle root extract because of its claimed effect of slowing the enlargement of the prostate.
Does it work? no idea, haven't seen any scientific proof that it does or doesnt so I'll use it for 6 months and then review whether to continue or not.
I have very few symptoms from BPH but if I can slow down the growth of the gland then that should delay the onset of future problems.