10 min @ 88-92% of... ? You say you don't have a heart rate monitor. 88-92% for only 10 minutes is on the far low end of adaptation for threshold improvement.
What are you trying to accomplish with 1 minute intervals? 1 minute intervals are too short for VO2max work, especially with 3 minute breaks to recover any anaerobic component.
The extra time is not likely to put you in an overtraining situation. Your list of riding times puts you in about 5-6 hours of on the bike time per week.
Guess it just depends on what you're trying to accomplish with your plan.
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