Ive done 3 now, all leisure, with my 4th one coming up in 3 weeks.
The first 2 were for 15 days and the third for 9 weeks.
I used the first 2 as a taster tour where i stayed in each location for a couple of days to see if i liked the place and on the 9 week tour spent more time at the places i really liked.

I always think its better to spend too little time at a place than too much.

Careful planning of the airline timetables can ensure you get time to see places.

I just love RTW's