It only takes one big one for me to call it a day.
There are very few occasions when I think catching #'s is fun ....
1. That day in the spring, right when the lake really starts to wake up from the winter. My usual bait of choice is a lipless crankbait. The number of fish you catch is only limited by the number of casts you can make. I seem to catch smaller fish on average, but there are usually a couple quality fish in there. That's what keeps me going and is about the only time I will stick with a technique that is catching #s. Because normally if you are into #s, you need to switch something up to get the big girls. Kind of gets you pumped for the rest of the season.
2. Topwater bite. Never get sick of seeing that no matter what the size.
3. Taking a newbie or kid fishing