FT8 versus WSPR

My impression is that I get better results on 6m FT8 than I do on 10m WSPR.  

Yes, on 6m FT8 I use 2.5W whereas recent tests on 10m WSPR have been at 500mW. 

Now, FT8, is supposed to be less sensitive at picking up weak signals than WSPR but WSPR needs almost 120 seconds whereas FT8 needs just 15 seconds. I suspect FT8 catches more, shorter, openings. Also, I suspect there are more FT8 users.