Sustainable BJJ

How do you develop sustainable BJJ? The kind of Jiu-Jitsu that allows you to train into old age? I’m only in the masters one bracket, but I’ve been doing BJJ over half my life. There are two ways that seem very effective in allowing you to keep training your whole life. One I will call the Professor Doug/Harold approach. This approach is the approach of shutting down offense and swiftly countering with great efficiency. The other is the Joe/Al approach where you play extreme defense looking for opportunities. I have seen both styles implemented in older grapplers, so I suppose like most things in BJJ it is a matter of personal preference