My 2003 Century tractor has a horrible seat. Even ten minutes, and it's uncomfortable. I read somewhere about cushions for people in wheelchairs being specially designed for sitting on, and thought that would be a good idea for my tractor. It was!!!!
That cushion is 21 years old and it's still comfortable. I keep it in my shop, in a safe, dry, easy to get to location where I can grab it on my way to the tractor.
I bought it off Ebay, but that's all I remember about getting it.
My new 2022 Massey 4707 came with an air seat. If you can get one of those for your tractor, I think you would be very happy with it. I can spend hours out mowing in that seat and feel comfortable. There is a limit, but it's not from the seat, it's from sitting for too long and not stretching my legs that becomes uncomfortable. But that is probably because I'm 58, being fat, and out of shape more then the seat.