If you feel your skills are diminishing, it's time for school. Go learn new skills from guys like, Dan Adams, or find someone thru a snowmobile club. If you're just over 50, you've got a lot of years to go. I'm only 46, but my father and his buddy are 75 and 76 years young. They keep up with us youngsters and we don't exactly ride the easy backcountry, to put it modestly.
They both ride 163s, one is turboed. I think that's the best length for older riders. I've ridden a 174 and thought it was just too much sled to throw around. Especially when stuck, and I stuck that 174 a lot! It was a Doo though...
80 years old, been sledding for 53 years, don't think school would help a lot