ode I can't say about all of them, but I did reshaft my Sim Max and a set of Callaways. With the Sim clubs they had the flyweight 66 g. Ventus shafts in them, and the irons just felt like crap all-around. I pulled the shafts, and then discovered the head weight thing. 6i was actually lighter than an old style 5i head, 254 g.. I've always, and will continue, to go with a 6i head in the range of 266, +/-. So, my 5i head needs to weigh (close to) 259 g.. I couldn't get what I was after when redoing the Sims, but it was close ,and they worked/felt great.
Others build differently, and it shows with the OEMs now, but it is the way I've always done it, with no complaints. I don't really pay attention to swingweight any more, fyi. I may put a 110g. steel shaft in, or I may use a 72+ graphite shaft, and still get the 'feel' I want. (same grip weight) That may be odd, but hell, look at me. 😂