Yes, don't give up. As mentioned in other posts, I've been searching for many, many, many years--digging through mountains of coins. With all that, I've found very little--it's the way it is. The key is time and volume of coins searched. As noted by others, try concentrating on one series/denomination for a while.
For perspective, keep your expectations somewhat reasonable. For those who search barns for long lost '57 Corvettes, they discover quickly that such finds are very few and far between. Might come across a ratty '74 Ford Maverick, however....