My horse was four when I bought the Circle Y. Since then he has gained two more inches in height and about 350 pounds (or more) but it has been NINE years. It fit him perfectly for about six years and I have just been slow to replace it.
Right now I am looking at a Circle Y with a gaited tree.
The only saddle that I have ever sold that I did not late go darn it would have fit the new horse was the draft saddle - I have Arabs and Arab crosses.
I can only hope the new saddle is as good as the old one!