The only thing I can say about that, is that it depends on the situation, but when something breaks, it puts you out-of-service for that particular job, unless another tractor is available to take over. And that's not always possible, if the broken tractor was using an attachment or implement specific to it. To me, a good farmer would take care of things in the off-season, while that particular tractor is not needed. So if there's a risk of something failing, be pro-active and fix it before it lets you down. For example, if I thought there was increased stress when a plow is attached, I'd rather fix it in the winter than wait until spring and find out when I start to plow.
REMEMBER: Keep it correct or you may face the