Long run for playing strategy ?

I have been running sims for some time and something has been bothering me:

Playing strategy variations (such as hitting 16 against 10 or not) seems to have very little effect on the return in the first 100 million hands compared to the standard deviation of returns.

In other words, you could play everyday for 25 years, and you would not notice the difference between playing BS and playing with, say, Illustrious 18 (I am not talking about Insurance which has a significant effect).

You would need to play several centuries before playing strategy variations start to have a significant effect on your returns.

Anybody noticed this ? Am I wrong ?