What you say! The CDP bonus saturates on the sixth day.
In addition, single tournament play gets the most XPs per hour - 190 for nine holes (25 mins), 400 for 18 holes (40 mins) plus the strokes you take. There are always "unlimited" weekly or monthly tournaments open. Thus it's easy 1100 XPs in 25 mins or 1300 in 40 mins daily.
A foursome, stroke or A/S, may get more XPs per game but it takes longer (1 hour per nine holes) and you always have the risk of forfeits => single game XPs or none at all.
IMHO, the former is for XPs and/or average play, the latter for recreation and company.