I did excellent on the heavy bag today. I'm going to tape a session soon to update my progress. It wasn't quite at 100% contact (until the very end) because I didn't have my wrists wrapped.
My rear hand doesn't drop, period.
Moreover, I'm exhibiting much better range as a result from not staying in and stuffing my blows. I've been practicing on starting at a distance and working from there before moving in.
I throw the lead jab as I rush in. As the distance closes, it takes less to retract my arm so I can go right to business.
This really helps in conceptualizing concrete maneuvers as a part of strategy, instead of just linking punches together on the spot.
Afterwards, I did hill sprints with an extra lap. My legs feel like the recipients of a knife storm. It'd be pretty funny if it was raining knives and you nonchalantly went out with an umbrella. That would rule.