to stop short of

[beachboy]

John McEnroe has always stopped just short of declaring Switzerland's Roger Federer as the greatest tennis player of all time, until now.

Is the expression to stop short of commonly used in everyday English? How else could I convey the same idea in a more natural way?

[bhaisahab]

John McEnroe has always stopped just short of declaring Switzerland's Roger Federer as the greatest tennis player of all time, until now.

Is the expression to stop short of commonly used in everyday English? How else could I convey the same idea in a more natural way?

Yes, "to stop short of" is commonly used and is perfectly natural. There are other ways to say it but they are not more natural.

[beachboy]

to stop short of = to decide not to do something
Does it necessarily refer to a decision made shortly before something happens? If I was planning to take a trip six months later, and then I decide not to take it, can I say I was planning to vist my aunt in San Diego at Christmas, but I´ve stopped just short of taking such a long trip?

[Raymott]

to stop short of = to decide not to do something
Does it necessarily refer to a decision made shortly before something happens? If I was planning to take a trip six months later, and then I decide not to take it, can I say I was planning to vist my aunt in San Diego at Christmas, but I´ve stopped just short of taking such a long trip?

No, it doesn't mean that. There's no time function involved.
It doesn't mean "to decide not to do something". It means to do something, but not quite completely. Not going all the way.

Here's a physical analogy:
If I decided to run 1500m, and I stopped at 1400m, then I stopped short of the finish. I stopped short of running 1500 meters. I didn't go all the way.

John McEnroe has always stopped just short of declaring Switzerland's Roger Federer as the greatest tennis player of all time, until now.

So, McEnroe hasn't gone all the way praising Federer. He might have said in past "he's good, he's great, he's a brilliant player", but he hasn't gone the extra distance to say "He's the best player of all time".

Here's some more examples:
She's pretty, she's attractive, but I'd stop short of saying she's beautiful. (I don't mind saying that she's good-looking, but I wouldn't go so far as to say she was beautiful).

To police: I never liked Bill. I tried not to talk to him. I avoided being in the same place as him. But I'd stop short of killing him!