There were some coins I sold when I thought I had made some porofirs, yeti blamed myself for selling them too early, considering the rate at which the coins were growing.
I made the mistake on so many occasions, which was why I told myself that, I will always try every means, as much as possible to see that, which ever token I see to have good future prospects, I would hold.
If you have invested in good tokens or coins then you should wait for the long term, there are many projects that are coming up with just hype and after hitting the market the price usually comes down. With all the said projects there will be a time when the price increases and from my experience i figured that it is better to sell when the price rallies in a certain coin and get out before it comes down crashing. I had some heavy losses in the past because of the said reason and i am not certain whether the price will ever increase again, but if you are investing in solid coins or tokens the price will increase when the market recovers.