So I would prefer to hold for as long as possible, since coins generally do well with time
You should know that not all coins do well over the time, the coin which you are holding will determine if you will make money even if you hold over time. If you are holding bitcoin, or other strong altcoins, then you should know that they are going to perform well over time, but if you are planning to hold shitcoin, then you should know that you are making a great mistake. Shitcoins are always hyped, and immediately the hype dies down, then the coin is also going down, so if you are planning to hold coins like that for long term, then you will end up losing your money. But if you are holding bitcoin and some strong altcoins, then you will be making profits over time.
Yes I think you're right, some coins do well over time but not all coins. Some will do well for some time but with time it will start depreciating in price. We have seen so many alt coins suffer in this manner,they started well but after a while they can't seem to be able to keep up.
The best thing to do before investing in altcoins is to first carry out research on the best one to invest in else you will just end up losing money. If you plan to invest in shit coins then you shouldn't hold for long because they are likely to fall again after sometime. Not all altcoins should be hold for a long time.
Just as Issa56 said, Bitcoin and some strong altcoins are recommended for long time holding not shit coins.