Selling and taking profit during the bull run is not ideal because after selling, you might not be able to buy back at the price that you bought before and this will make you have less bitcoin that the initial amount that you had before selling.
Even that said time you would have entered the market could be a late one to other investors because they would have done theirs along time ago, there's a need for us to understand that bitcoin can always serve us the opportunity of an invest each time we think we are ready to invest as long as there's going to be enough time to hold, investing and selling after taking your profit is not a bad idea, as long as you're going to reinvest on bitcoin, what may be also required is for another season of holding, that's why you can enter the market at any time provided that you're willing and able to hodl.
Meaning that you don't have a bitcoin target and you are not focus on accumulating bitcoin on a long term investment.
For the benefit of those that may not be able to hodl for long, they may engage into making trades on a short range intervals, making an investment should be done at ease and will always be profitable as long as we are not rushing to invest or to sell either, we also can make use of any strategy to make the necessary preparation towards the intended duration we want to go through, just to have the best experience when we hodl.