I wouldn't be so sure if I were you.
Wii Sports (Released November 2006)
Current Rank: #4 Last Month’s Rank: #4
Raw data for “Wii Sports” usage
Average time played per player:
As of 1/1: 34 hours, 47 minutes (down 36 minutes)
As of 12/1: 35 hours, 23 minutes
As of 11/2: 35 hours, 4 minutes
As of 10/5: 34 hours, 45 minutes
As of 9/1: 34 hours, 25 minutes
Average number of sessions per player:
As of 1/1: 28.38 sessionss (down .66 sessions)
As of 12/1: 29.04 sessions
As of 11/2: 28.9 sessions
As of 10/5: 28.72 sessions
As of 9/1: 28.56 sessions
Source