Erect/Semi-Erect Stretching

When I did PE a couple of years ago, i got the program from one of those pay sites. I remember that part of the warm up was erect or semi-erect stretching also. Anyone think that it effective and/or detrimental?

I think it can be effective, but for maximum lig and tunica stretch, as flaccid as I can get it seems to work best for me…