It's completely up to you how many coins you want in your portfolio. Some crypto's can be seen as ''high risk/high reward'' or ''Low risk/low reward''. Most time low market cap coins are considered high risk/high reward, and crypto's with a high market cap considered low risk/low reward. It just depends how much money you want to make/are willing to lose. Always do your own research and only invest what you can afford to lose!
I would not say having too much is a bad idea as that would depend on how well you are able to handle all of them at once. In most cases anyway, we all know basically that the more you can invest in as long as you know what you are investing in, the chances of you to at least diversify and get something across board in the long run.
For most altcoins, it is glaring they seem to have a season and using them to increase my bitcoin folio over the years has been a thing for me. What is just important with your portfolio is to know you are holding potential coins; you can handle and manage yourself when it comes to risk, and you have the knowledge to keep making good decisions.
