An example from Taleb
“ Over short time increment, one observes the variability of the portfolio, not the returns.”
--Nassim Taleb
In his book, Fooled by Randomness, he gives an interesting example.
A 15% return with a 10% volatility per annum translates into a 93% probability of a success in any given year.

This means if you check your portfolio once a year, there is a 93% probability of seeing a positive result.

If you check the portfolio every day, then there is only 54% probability of seeing a positive result.

For one month, it is 67% and for one quarter it is 77%. Seeing negative results in portfolio would trigger. Unpleasant emotions resulting in inappropriate action. That’s why most investors are unable to stay the course.

If you see your portfolio only once a year, the probability of negative results come down significantly. This would ensure that you have sufficient emotional strength to stay the course.

From 1979-80 to 2015-16, for the last 46 financial years, we had 31 years of positive Sensex returns and 15 years of negative returns. So since 1979 the Indian Stock Market has produced an annual gain 68% of the time or 31 times while losing ground just 15 times.

So even in real life scenario, if you check the portfolio once a year, the probability of seeing a positive return is high.

So don’t check your portfolio frequently.

P.S. - Honest confession I check or review my and family portfolio twice in a year.