I agree with that comment.Be careful about checking every day…
I have a spread sheet of all our investments that I fill with current values on the last Saturday of every month (to get rid of any time of the month or day of the week issues), and record any assets that are going against the mainstream. That takes about an hour once a month. I don't trade a lot - Warren Buffet would describe my approach as "sloth". I keep winners and trade only when something is moving in the wrong direction over time. That minimizes trading costs, bid/ask spreads, and taxes.
I research mutual funds (and more recently ETFs) carefully before I buy them, and would allow 2 - 3 years of under-performance against peers before I dump them - and then never look back. As you might suppose, that doesn't happen very often. I would sell a stock after months of under-performance (against its peers) and especially accumulating bad news (I read the financial news daily).
On New Year's day every year I make a serious effort to accurately calculate our family's Net Worth. That takes 3 or 4 hours once a year. Doing that has taught me to minimize vehicle purchases. New cars contribute a major loss of value every year. That's why I buy quality vehicles and keep them for 15 - 20 years.
My approach is methodical and possibly tedious. Has it worked? Oh yeah, has it ever.