I would also include the price of the equipment in the calculation. During a gold rush, not only does your equipment make more $$$, but the value of the equipment goes up. Let's say you own a few Antminer L3++'s and DOGE boomed, so you made a killing. The DOGE price is starting to fall. You can make even more profit by selling your equipment, then using all the funds to buy hardware for other algos that aren't overpriced.

Likewise, during a bear market, not only does your profit margin get squeezed; but your equipment falls in value too. It's better to try to sell if the price has went downhill for 1-2 months and the momentum has ended.