Eastern Cougar,
Eight pound wouldn't help you, but it certainly wouldn't shut you out either. More likely than not you either weren't fishing where there were a lot fish, (or any fish), or you were fishing were others had fished it hard first.
This time of year if you are looking to catch fish in large numbers using a small roostertail, regardless of the whether you are using 8lb test, is your best shot. If they are there, at the very least you will be getting "flashes". More importantly it allows you to cover a lot of water so you don't spend time dredging the bottom in dead water with bait. Believe me I have been a crazy trout fisherman for the better part of 30 years, (I am only 35), and I can tell you that a guy that knows how to fish a roostertail on opening day will always outfish a baitfisherman! (The obvious reason being that the roostertail fisherman can cover far more water and make presentations to fresh fish as they constantly move to fresh water...The only exception being in extremely high spring flood waters, in which case no one does well.) Case in point last week in less than a few hours I caught well over 30 trout on roostertails and left them biting....
JC