I see no point why an investor who intends to hold bitcoin for long, should always monitor price movements. The focus of an investor who wants to invest or already investing in bitcoin should always be on accumulating bitcoins to his or her capacity with funds that can be afford to lose. Traders are the once whom are know for constant monitoring of there trade in order to know when to take profits and close there market, that’s not the mindset of a bitcoin investor.
That should be true, but I think some investors who intend to hold Bitcoin in the long term also often look at Bitcoin price movements to be able to enter at the lowest price to get the best price so they can accumulate more Bitcoin and I think that's not wrong even though an investor also uses the DCA strategy to accumulate Bitcoin, but sometimes when the price correction is very deep, someone will change the strategy so that they can be more profitable by buying Bitcoin in larger quantities than usual.