My own system is very simple. It doesnt matter when I buy, I could buy at an ATH or midway between an ATH and an ATL; but for the sake of security I would always sell at an ATH. This system assumes there would always be a correction following an ATH, sometimes a very damaging correction that it becomes a perceived market crash. No matter when I buy, provided I don't run into some life threatening issue, I believe there would always be a new ATH, so I wait, and I sell immediately that ATH comes. The I sit back and watch the greed and FOMO take over, wait for the correction, then buy again. Rinse and repeat. The only constant that this formula relies on is that there would always be a new ATH. So far this fact is yet to be disputed.
What is your system?
Mine is similar to yours, though we all want to buy the bottom there is always the fact that we cannot predict for sure how the market is going to turn out so that way it is best to just hold through it all. When I buy the coins,I buy them with the mindset that I am not selling off any of it until I see another all time high of the coins, that is only when I sell.