As there are no title fights scheduled until at least February 2020, we can look at 3 years of title fights in slight advance. Here are the number of full title defences or vacant title fights for the real belt (not interim) in each UFC division from February 1 2018 - 2021.
Men
HW: 3
LHW: 5
MW: 3
WW: 4
LW: 3
FW: 4
BW: 4
FLW: 5
Women
FW: 3
BW: 3
SW: 5
FW: 4
Average 3.8 - or 1 title defence every 288 days.
If every challenger of each belt all got rematches, then on average, it would be 2 1/2 years between the last fresh challenger and a new one getting a title shot.
Men
HW: 3
LHW: 5
MW: 3
WW: 4
LW: 3
FW: 4
BW: 4
FLW: 5
Women
FW: 3
BW: 3
SW: 5
FW: 4
Average 3.8 - or 1 title defence every 288 days.
If every challenger of each belt all got rematches, then on average, it would be 2 1/2 years between the last fresh challenger and a new one getting a title shot.