In my opinion, for the average player it breaks down like this...
In any one hand luck probably has up to an 100% chance of determining the outcome. In an 4 hour session, luck probably makes up about 85% of the results. Over a week of regular play its probably down to around 75%. A month of regular play and its maybe 66%.
Keep in mind that luck works both ways too. Some days you get chicken, other days you get feathers.
It takes a long time for the averages to catch up just to be statistically even. Sure, aces will hold up XX% of the time, but you to get dealt aces a few hundred times in order to realize that percentage.
Finally, the long term number I think is about right...
In the average grinder's lifetime, luck has probably been cut to about 45%. The best in the world may peak at 40%. Maybe.
A 20% edge seems huge to me, but what do I know.