Yes, the steps become very long for high levels, exceeding 100.000 XPs above lvl 92.
Blitz and CTTH give only little XPs, multiplayer games last long and bear the risk of disconnection or quitting, thus less recommendable for any numbers (XPs, average). Play them just for fun.
Best XPs come from the "continuous days played bonus", CDP, which maximizes to 880 XPs after six days. Be careful to play once every day in GMT (UTC 0) time. If short on time, just play one hole via the WGT Community / Golf Courses tab. It counts (882 XPs minimum), just like any practice round (see 3 holes random practice).
Good and reliable XPs come from strokeplay games, and these are doubled for tournaments.
9 holes: regular 95 / tournament 190 XPs, 18 holes: 200 / 400 XPs.
Add 1 XP per stroke.
Thus, a single game like 18 hole tournament with CDP may add to 880 + 400 + 61 = 1341 XPs.
My nickel: Stay away from XP boosts, expensive with little reward.
And, don't play for numbers, just play for fun - it's a gaming and recreation site!