It’s worth reading this thread about VLaMax. This describes some fundamentals on physiology behind time to exhaustion and aerobic performance. Once I understood the concept, it was a helpful way to frame training goals, and the kinds of sessions to accomplish those goals.
I’m a similar profile to you, high anaerobic capability, fast twitcher.
Long sweet spot intervals (20 mins+) are very effective at improving aerobic capabilities. But important to not ride at too high a power. With some TR plans, the “sweet spot” session are more like threshold, and if your FTP is overestimated, it’s easy for these to become too hard.
Using a heart rate cap is an effective way to ensure you’re not going too hard during SS intervals. Eg use a HR cap of 85% of max.
This post has some good info on this approach:
And the following post has good ideas about a sweet spot progression to follow:
And longer, lower intensity endurance rides are very helpful/needed also - especially if you are doing more than a few hours a week. Ie Don’t just do sweet spot, it will likely be too much.
At some point in your training, you’ll need to think about VO2max work in addition to endurance and sweet spot. But that can come later.