Wireless
This is certainly true in my experience crew members particularly Captains but also F/O's are making such choices. There are other reasons however rather just fatigue;
The tax man and his thresholds.
Commuting
In the case of one UK AOC if you live outside the normal commuting distances (by road or air) you have to have a 90% contract (the % may be less 75%?) and rather than having the 10% in leave its given in days off so crews get more days off in the roster and thus less commuting and by default fatigue.
Its the way forward IMHO