I just use standard rules for jumping, no check if it's your strength or less. I guess I have had someone try to jump further. I just took the specific situation into account and did the standard difficulty setting call. I let the player know approximate difficulty* and we go from there. So what are they jumping? Roof to roof? Slanted tile roof or flat top? It's probably going to be roughly the same DC, but the result of failure is likely to vary from "you slide off" for the former to "you manage to grab on to the ledge but you can barely hold on.Well, compare it to magic items in D&D, rare and unique means pretty kick ass IMO!
Oh, it could be anything really. It is more about establishing your "ruling" for future use and it standardizes it for new players, so they know what to expect in those situations.
For example:
In my last game PCs are in a basement storage area with a variety of crates and barrels. One of the PCs decided to jump on top of a crate to get better positioning. I decided that the crates had been down there a long time, they may not be completely safe to stand on. So I let the player it was an easy acrobatics check getting on and off but there was a possibility they could fall off.
It's rulings over rules, taking into consideration a nearly infinite number of variables based on the scene and then setting a DC I think is appropriate. Which is the way the game is designed to run, no house rules. Since the DC can vary from scene to scene there's no need to codify it.
So unlike the last couple of editions the authors didn't try to lock down everything, it's one of the main differences that I see between 5E and the previous 2.5 editions and hearkens back to the 20th century versions of the game.
*Based on what they can see. Most of the time there's no difference between perceived difficulty/result of failure.