Wouldn't it as well be smart to say that accumulation stage should go on for as long as it is realistic that bitcoin will be in accumulation stage. For example, if I reach my goal and own like 1 BTC, but I see the statistics and know that 2% of the world's population now own BTC, but regulatory bodies are more prone to support BTC development and purchases through government organizations and businesses and it becomes evident that they are not against BTC. They pass laws that allow non-custodial wallets without sending you though cumbersome processes like KYC for every address you own and many other bad things. You realize that BTC has a bright future and you also realize that barely one owns it, would it then be right to stop accumulating when probability is high that BTC accumulation is only about to get started?
I think the right decision would be to then maybe adjust your goal and accumulate further as your estimate is that the market has upside potential. Unless you reached certain limits within your wealth distribution preferences, but stopping when you see it is about to get going should perhaps alter the first decision.
In my own perspective, I think that the ideal time you feels like you have accumulated enough Bitcoin is up too you as an individual, though as humans we always want more, but in life we will definitely get to that level where within us, we can admit that if we stop now, we can as well be ok with what we have, so till we get to that point, I don't see any reason to stop accumulating Bitcoin when it's still very cheap as now.
Lastly, we all know that the stash of Bitcoin in your possession determine how wealthy and profitable you might become in the future, so till you get to that point of satisfaction, you wouldn't even see any reason to stop accumulating Bitcoin, because you aren't satisfy with your current stash of Bitcoin in your possession.
Being ok with what you have implies that you found something to preserve the value you own. If you are ok with having $100,000 in the bank, it doesn't mean those $100,000 buy you the same things next year as they do today. That is why you are constantly supposed to take actions to preserve value if you are at a point where you are ok with what you have. That is what makes bitcoin so interesting as it has more upside potential than other assets I think and its scarcity is set in stone.
Other assets are subject to variables you can only guess. If the population rises, more housing is required. Consequently more houses are built, but suddenly due to demographic circumstances, population decreases and housing might not be needed as much, meaning it could decrease in value as demand decreases while supply was increased to meet a demand from the past.
Bitcoin is subject to less variables. This doesn't the variables are not extremely important and impactful, but the scarcity factor remains forever, which means the supply side is set in stone. Now you can do some philosophy about the demand sind of course, but having a fixed supply side that you yourself can verify is of great importance.