Thomas Shey
Legend
Im not sure the best formula though i think its less levels, to the chagrin of folks who want 30 level D&D, I just dont ever see that in the cards anymore in face of the amount of folks that barely get past 10.
A lot of that turns on two things:
1. How long do people play?
2. How fast are they willing to let levelling go?
As an example, in theory 13th Age characters level every four sessions (in practice its slower than that in most cases after the first tier of play (L1-3) though they only go to level 10 (but 10 is also probably equivalent to 20 in most D20 games). Shadow of the Demon Lord/Weird Wizard goes even faster, levelling after each adventure (and adventures are sort-of assumed to be one session operations, though that's probably assuming a longer gaming day than those folks who play for 2-3 hours do).
So a 30 level D&D version where people levelled every session wouldn't necessarily be beyond the reach of everyone. It might feel too fast for various reasons, but that's a different issue and is partly based on other design elements.