I actually visited every one of neighbors in one sitting last night for the first time since about Saturday. I probably only make it through the whole list once or twice a week, but I visit some nearly every day.
I kept track of who had anything open to tap or graffiti, and I could collect fps from about 75% of my neighbors, but thanks to EA's step down system for fps you can collect each day, I was able to collect 92% of all of the possible fps I could from my neighbors.
I like EA's fp system because the % lost is so small, we're not penalized all that much for missing neighbors each day. Missing that small of an amount maybe puts me a few days behind on earning the fp prizes than others who visit all their neighbors each day, but I don't mind.
Likewise, the impact of fps I get from cleaning graffiti is so small (max 4-8 points a day for me since I don't log on every few hours) that I don't mind if my neighbors don't graffiti even if they can.