Starting with the theoretical constraints of rotation and scoring:
#1 and #2 are ~16.3% likely - say 1 chance in 6, or 5 to 1
#7 is ~8.8% likely - say 1 chance in 11, or 10 to 1
Now add your abilities, condition, temperament, partner affinities
(whatever turns you on), and how far up or down can you go from
that? A good question.
1 chance in 3 seems like a push to me - I think I'd say 1 in 4, but that's still a stupendous rate. On the long end, the 1 in 20 sounds about right.
I add a routine to my history anaylzer to see how high/low my individual ratings actually get.
It's actually a problem I deal with in my analysis, i.e., how big a spread should I allow between best and worst.