There’s no theory that allows an increase the block production rate. A difficulty drop won’t accumulate more than 1 round unless hashrate drops. You want it to drop if that happens. Difficulty can’t drop more 1.2% in 1 and only 1 round if the reverse limit is 7200 and the attacker sets the last block to 7200 in the future. There’s no average decrease in difficulty because it will cause an increase in difficulty in the next round.