I've never considered time spent fishing Cave Run a 'waste', I'd think if you have the opportunity, come on up and give it a run. You sure can't catch them if you're at home on the couch.
I would recommend getting one of Tony's guides for a day if this is your first time on the Cave, these guys can really shorten your learning curve if you can get one booked on short notice.
Also, there's a $3 ramp parking fee at each launch, so you'll need a hang tag for your vehicle and they can be purchased at most area convenience stores and gas stations. Just saying so you won't get to the ramp and have to run back into town. Cave Run is a beautiful lake in any season. Enjoy! m