There's mass weight for recoil reduction, and then there's mass weight for helping with aiming steadiness.

For recoil reduction- you can never have too much mass. The more mass you have, the more energy it takes to move that mass into felt recoil. Modern bows have been designed with getting them light, yet fairly recoil free.

For aiming steadiness- that's an entirely personal thing. You definitely can have too much mass real quick. I found that out through lots of shooting over the last few years. There's a point in the mass weight addition that I start to hold less steady than a lighter version of my setup.

I was always of the mindset that heavier is better, so I'll just build up my holding muscles to be able to hold that heavier amount steady. So I had extra weights that I milled out put here and there on my bow and stabilizer system. It balanced beautifully in my hand, but if I tended to go long on my shot- I'd really start to drift. I'm hard-headed, but after enough of something not quite working I will try something else. So I stripped off a lot of weights and shot some rounds and realized that I was holding steadier longer. Maybe not quite as rock solid at the initial draw, but throughout the shot I was able to maintain sufficient holding for good accuracy. So just keep in mind that for some people looking for that holy grail of mass weight steadiness for target archery, it can be a long process of trial and error. Too little, and too much of mass weight can both be detrimental to your score. Every individual has to find their happy medium that works for them.