What I would do is after a longer medium distance ride go out for a few miles on flatish roads & undergear the bike. Just spin as fast as you feel comfortable doing so for a long period, ignore the speed it's irrelevant, just simply track what cadence you were doing approximately. This will give you an idea of what range you naturally ride in, you can get a more accurate idea of your optimal cadence with a turbo trainer (keep going up the gears until you get to the gear you're turning the fastest then record what your cadence was at that point) but it'll get you in the ball park.
As WR said, everyone is different , I often ride with a guy who I'm fairly well matched with for pace. He spins at 60-85ppm & will keep in that range for hours on end & when he wants to put in a spurt will gear up & grind it out. I on the other hand am spinning between 90 & 110ppm & to put on my spurt will be pushing the ppm beyond 140, on 2 occasions in the last month it's been over 165ppm for 30s or so on the flat!