I'd suggest alternating each week between six 200 meter sprints and six 1m intervals. Both should get 4-5 minutes of recovery (barely pushing the pedals and/or coasting). These should be explosive. Start out of the saddle for the first 10s. They should hurt. Try to rip the cleats off your shoes and break your chain. Bend your handle bars. Every single pedal stroke should have as much power as you can generate. Do not pace these efforts at all -- just insane power. If you think you are fading, go harder until you know you're fading, and fight the fade until you ride yourself into a pile crap.

Yeah, so alternate sprints one week, 1m intervals the next.

Each week do VO2Max intervals. 5x5 minute Hill repeats are great if you have access to ~1 mile hills. 5 minutes of recover it plenty for these. Pace each one to hurt. Some weeks you hit the first one for record time, then suffer through the rest. Other weeks, try to nail the same time all 5 runs, but go fast enough that you can barely finish the 5th one on time.

For the other rides, you can do 3x10 minute intervals or 2x20 minute intervals. I'd probably just choose one and do no more than one of these workouts each week. You can skip them some weeks too if you replace it with fast tempo work.

For the fast tempo, a.k.a. SST (sweet spot training), you want to ride hard enough that you can do it for 45-90 minutes, and still have a good ride the next day. This is not a race effort, but too hard to carry a conversation. You should be going hard enough that you occasionally catch yourself backing off and have to redouble your concentration.

SST is your bread and butter. I just started doing these rides in December, and my threshold power has gone up a full 10% in those ~11 weeks. It takes a week or two to get used to riding at this level, because it's kind of hard. Once you adjust to this low-level constant suffering, you'll really start to get stronger. It's pretty amazing.

A 200m sprint workout can be done in less than 30 minutes, so if you have time, you can do an endurance ride at a fairly easy pace afterwards.

Every couple weeks, if you're not racing it's a good idea to go on a group ride with racers (including elite and pro if possible). Do what you can to hang on and learn from it. Take some risks (attacking and such) if you feel strong enough. Count these as SST rides even though the intensity is so much more variable.

Another side of SST I haven't experimented too much with is low-intensity intervals. A fast, small paceline would work great for this. Riding solo, you could go for a minute at your TT pace, then try to recover while keeping some pressure on for a minute or two, then repeat.