Not only that . . . but, every revolver is different and what all the mainspring has to overcome (handspring tension, left side hand / frame surface, ratchet angle, ratchet surface condition, hand tip condition, left bolt arm tension (related to thickness/length), bolt arm reset cut angle and surface condition, cam height and surface condition as well as transition to cam, hammer screw hole friction, hammer screw friction, hammer side surface condition, and . . . hammer roll condition!) If it was the same in every revolver, then a "so and so" spring would be expected to have the same result in all of them but. . . . they aren't . . . lol!!!
You'll just have to do the install and test regiment.
If you find what "feels good" to you but is too light for reliability or ignition at all, you'd be amazed at how well that same spring would do if you minimize the friction from that list o stuff ^^.
Mike