Frankly speaking, if you are not in the actual situation, it's easy to give advice on what to do.
But if you are on the actual situation, I doubt most people will be able to follow those advices. Even putting bitcoin on something you can't access easily, you will do everything just to access it especially during a crazy bull run since you don't want to missed it.
I don't even buy the idea of locking our bitcoin in a platform for a specified period of time since we aren't fully in control of the platform, and if something bad happens at the backend of the platform where we lock our bitcoin, we will not be aware, and we might possibly lose our bitcoin because it is not you key, not your coin. If any investor knows that checking his or her bitcoin portfolio all the time will make him or her sell his or her bitcoin too early, he or she should just keep his or her wallet's private key or seed phrase safe and uninstall his or her bitcoin wallet on his or her device so that he or she will not have access to his or her wallet at the time of his or her bitcoin accumulation journey.
Your suggestion to not be tempted to sell Bitcoin may help many investors to be more practical about the way, but I think it may not be possible for most. People are more motivated to see their wealth in front of their eyes and they start dreaming about the future with it. The idea of locking in for a fixed period of time is the opposite of the possibility of increasing holdings for investors which can make them lazy and spend their allocated money on other sectors due to irregular savings.
When you keep investing Bitcoin regularly, you have a plan every month or week according to which you can easily reach your goals. If someone says that considering locking in a portfolio during bearish or bullish times, it may be an immature decision. I would recommend that you do it regularly and continuously for accumulation Bitcoin at any amount because you never know when the future may be more better for you.