I think so too.
Maybe I'm just being naive, but it's interesting to me that I don't see more people training with a heavy bike/gear setup to make it harder on themselves- it seems like the current thinking is to make it as easy as possible (light bike, no gear, clothing, etc).
Can someone explain this?
I'm not a roadie, just a commuter, but I accidentally did that. I commute year round, and didn't feel comfortable on the road bike at night on our leaf/acorn/rock/dead rodent strewn roads, so I took to my 40 pound CroMo hybrid, vintage 1992, for about 4 months. Flash forward to March, out comes the road bike, and I'm taking a hill on my commute at 18 mph that I used to bottom out at 16.
I truly think that pushing that beast uphill for a few months really helped. As others have pointed out, I suppose I could have just pushed it harder on the road bike anyway (since it has, like, gears and stuff). But for some reason I think the beast bike helped. I don't know if it was the psychological impact of seeing single digit speeds on the cyclocomputer and saying 'Oh *hell* no' or what. But I sure noticed a difference come spring.