It is just a minute of your life to check on it, and we should do it. That is really my routine every morning just to check the price of altcoins and check for new news about them. That is really a missed opportunity, but again, it is your choice to check from time to time because others won't as they will be tempted to sell their assets, which again is their strategy. But the best way to do it is to check the news of the altcoins that you are holding to see any updates.
It is true that it does not seem to be a big deal to check your coins at least once a day, but when people are holding 20 coins or more then suddenly things are not so simple as now not only they need to check the price of so many coins but also the news related to them, and people could easily spend an hour doing this, and if we add that the movements of altcoins are incredibly fast then you could miss the movement of one of your coins even if you were to check your coins once a day, so another method needs to be used in order to deal with those fast movements.