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.
This is called timing the market, if one can do it as perfectly as you describe it, they would be better off with just trading and not having to deal with all the mess associated with mining gears.
treating the gear as if you are holding that asset it mines is just a bad idea, when you invest in a mining gear it has to generate more of that given asset than you could otherwise buy with the cash you are willing to invest, or else, it's just a losing game, as it stands right now, most new gears have over 1 year ROI, thanks to the unlimited money supply the U.S investors have, they are throwing money at Bitmain and MicroBT and now Intel, like there is no tomorrow, some of them, will go broke that is for sure, but to many of them they don't play our rules, they recycle otherwise wasted energy and mine at a cost near zero, you are competing against those same people, so good luck.