I ran into this blog post on the topic of ejector rod lengths that I thought was rather interesting:
https://revolverguy.com/ejector-rod-length/
The author measured the actual ejector throw of a number of different revolvers. The relationship between ejector throw and barrel length wasn't entirely linear. A bunch of measurements were from other than Smith & Wesson's but there are several of those also listed.
(The barrel of my Ruger Speed Six is 2 3/4", so I'm not sure if it is relevant when discussing 2 1/2" vs. 3" barrels. And it is, of course, a Ruger. But I have never had any issues ejecting hot loaded magnum brass from dirty chambers with that gun. The ejector throw is what I would call "full length" in that gun.)