Hi.
I’m planning on doing 12 weeks of base. My race season (nyc area) typically runs from march-aug/sept. Am i setting myself up for failure/burnout by doing stretch & breakthrough level workouts early on in base? Is it better to do step by step productive or is it better to really push myself to in an effort to see how far i can actually progress.
I’m sure the answer is “it depends”. I would love to hear your stories and your wisdom.
I don’t see any harm in doing some stretch or break thru workouts as long as the majority of your workouts are out of the base plan.
I mean… It tends to be better to go step-by-step productive. 
However, I’ve looked at your account and you have a solid training history, so I think it wouldn’t be a bad thing to try! Besides, you still have August/September left of race season, so if anything these efforts can be beneficial and mimic the demands of racing.
Just be careful of overdoing it. Listen to your body and rest if needed. Also, try and time these harder workouts in your Calendar in a way that you’re not burning out before you even get to race day.
After your race season, I would highly encourage a proper base. But that’s my take on it 
I’ve occasionally had stretch and breakthrough workouts in my plan which haven’t adapted out so I’ve done them.