I'm tempted to have a go just to make 50s seem shorter :-)
Yes, I think this is a valid reason.
Riding a 12 to make 100's seem shorter doesn't really work since it will probably take the rest of the season (or possibly, your life) to recover.
Although I don't feel good for a couple of days after a 100 it doesn't take that long before there seems to be a beneficial effect. Even if it's only that the other distances *seem *shorter it's still worth having.
Yes, I think this is a valid reason.
Riding a 12 to make 100's seem shorter doesn't really work since it will probably take the rest of the season (or possibly, your life) to recover.
Although I don't feel good for a couple of days after a 100 it doesn't take that long before there seems to be a beneficial effect. Even if it's only that the other distances *seem *shorter it's still worth having.