No I just replace the mainspring when I get 'em.
A new (to me) gun with unknown history & round county typically gets every single spring replaced with new. I'll replace the mainspring with a standard weight 20# when I go through the gun in detail then I'll pretty much forget about it. I'd only mess with it again if I noted some signs of early unlocking on the brass (ie. case bulges)which could not be attributed to something else. In which case I could either bump up the recoil spring to one exerting more force when in battery (will likely alter ejection pattern) or... increase the weight of the mainspring (will increase DA trigger weight).
There's a delicate balancing act going on here between the slide's mass, the recoil spring, mainspring and the load power.
For the most part the engineers at S&W had this all figured out. In other cases not so much (4516-1 for example was undersprung IMO).
On a used gun, you never know if the mainspring has been changed to something other than spec or is just plain worn out. On older guns like the OP's first & second gens those mainsprings might just be tired. Can't hurt to stick a new one in there and not worry about it for another 40 or 50 years
Cheers
Bill