This is why even a MV plan with a ton of weekend volume doesn’t work for most of us. Try dropping down to a LV plan (still sometimes too much intensity IMO) and allow for that weekend endurance you’re clearly enjoying. The only time I even attempt MV is when I know I can’t ride outdoors for extended periods, in the winter. LV leaves me with enough focus to get faster on structure days and enough energy to enjoy endurance riding.
Most people should have a laser focus on nailing a maximum of two HIIT structure days, then adding in riding volume in the form of longer, and perhaps more fun riding.
You’ll need to balance the desire for 100% MV plan compliance, and riding outdoors for your soul. OR, just drop down to LV (and be prepared to make modifications to that).