Enduro mtb training whats best?

Hello, I’ve ridden mountain bikes for years, i was about to hit 40 and decided it was time to race and do some local enduro events before i did. Did one season and discovered i had an underlying heart condition so a year off and a pacemaker later I’ve been given the all clear to race again. Fitness has taken a big hit so whats the best way to go. I am currently on the sweetspot base which i was going to follow with short power build then gravity speciality. To throw a spanner in the works id like to take on some Duathlons as well. So i am wondering if i should do anything different think i might be specialising a bit too much

On the bike training is key for Enduro and I would prioritise riding time over turbo sessions when and where possible.
Any training you perform can be applied to both disciplines it’s a case of looking at the demands of the event and seeing what they require. How long is the cycling part of a typical duathlon?