Doesn't congress "investigate" all kinds of stuff where the investigations go nowhere? Aren't most congressional investigations just opportunities for congress

Doesn't congress "investigate" all kinds of stuff where the investigations go nowhere? Aren't most congressional investigations just opportunities for congresspeople to read statements directed at their supporters? I'm just confused by all of these investigations. I want to hear about the proportion of investigations that elicited information that subsequently induced congress to write and pass new laws. Can anyone point me in that direction?