I always scout the players suggested to me, have never attended 1 though. I've found when managing in BSP/N/S a few of the players are very good for the leagues. I signed a GK for Eastleigh in the BSS once who has the PA of a L1 or Championship GK I think it was, good enough to go straight into my lineup and my GK pretty much the whole game.
Not worth it if you're a good team, sometimes good when your managing in LLM though. First season trial days contain shocking players though.