As others mentioned, what qualifies as heavy to you?
Personally I like to run 32 spokes and with modern materials I have no trouble believing that's fine for anyone who doesn't try to smash their way through things and weighs under 300 though that starts to push the limit. From about 280 and up I prefer to build 36h and have a friend who is still riding the same sat of 36h wheels I built for him 7 or 8 years ago. His weight fluctuates from the 340s to as high as 380 at one point, for several of those years he was riding 300 miles a month and still tries to ride several times a week weather dependent. In that time the wheels have needed one truing and no spokes. Good hub, 9sp xt at the time, with a Sun rhino lite, 36h, butted spokes and higher side of proper spoke tension. Nothing grand or glorious, just incredibly reliable as he needed.
Now a days I can't image building a 40h unless maybe you're getting close to 400lb and 48h would seem like a waste of spokes, I'd sooner move to a 13/14 single butted spoke like I would use on a loaded touring bike or a tandem.

I got an answer, and some comments to consider.

I am 300lbs and the wheel has 32 spokes. I spoke to the guy who built the wheel, he saw me and the bike, and told me that they laced the wheels in-house. The return visit was more than a once-over, and it occurred to me that they couldn't really make money with the amount of time they put into it. A shame, I guess.

I really like the sound of an IGH wheel, but it might be overkill right now.

Thanks to all for comments and ideas.

A radical idea, which you may or may not think is a good idea.

https://www.bikeforums.net/clydesdal...l#post21406300

Very interesting.