Do you want the "decathlon example" again?
If you make a "decathlon" consisting in 10 events EACH ONE OF THEM being the 100 metres track race, then probably the best at that, for example, Usain Bolt, would win probably 9 or even the 10 events. This is "homogeneous conditions".
Instead, if you make a "real" decathlon, with 10 totally different events ( 100 metres, long jump, shot put, high jump, 400 metres, 110 metres hurdles, discus throw, pole vault, javelin throw, 1500 metres), you won't see a single athlete winning the ten different events. This is "NOT homogeneous conditions".
This is an exaggeration, of course. But you can easily understand the idea.
In the last ten years in tennis, it is MUCH MUCH MORE EASY for the best (or the two best) tennis players to win EVERYTHING (and so winning a very high number of GS tournaments) than in any other former era.
For the very same reason, for those not being the very two or three best players in the world (for those who rank between nš4 and say nš20 ) it is much more difficult to win a GS in this era than in any other former era.
Homogeneus conditions produce logically this result (very few players, one or two mostly, winning almost all the GS tournaments, and very difficult for a non-top-10 player to win a GS).
Varied conditions and different competitive playing styles (like it alwas was in tennis) produce logically the opposite effect (more different players winning GS tournaments, but much more difficult for one player or two to win 10+ GS).
This is "the decathlon example" for those that do not understand what is going on in tennis in the last 10 years or so.