I'm not going to argue with someone as everyone's experiences are different. This distribution pretty much summed up my live experience. I've done a lot more math on this subject then most people as well.
http://www.pokerdope.com/poker-variance-calculator/ Is a fun tool to play around with and I used to mess with when I was more obsessed with determining what my actual winrate was.
Downswings in numbers
For this anlysis a downswing is defined as any period where the current total winnings are below the maximum previous total winnings. Any downswing is considered to last until the total winnings at least equal the previous peak.
The following tables are derived by a simulation over 100 million hands. The first one shows how often the simulated player was in the middle of a downswing of at least X BB, the second one how often he was in a downswing which lasted at least X hands.
In general these simulations underestimate the likelyhood and extent of downswings.
Occurrence rates for downswing extents and downswing stretches for a player with a 30.00 BB/100 winrate and a 400.00 BB/100 standard deviation.
Downswing extents
300+ BB 68.75%
500+ BB 67.44%
750+ BB 65.74%
1000+ BB 63.75%
1500+ BB 59.67%
2000+ BB 55.03%
3000+ BB 45.77%
5000+ BB 30.36%
7500+ BB 15.80%
10000+ BB 7.93%
15000+ BB 1.37%
20000+ BB 0.46%