There is not a right answer for that question, diversification without a doubt is very important if you are investing a huge amount of money in this market, but diversification is only a way to get to your goal, your goal should be to make money out of this market and if you can make money with one coin or with one hundred then it makes no difference, try to find a way to make money in which you feel comfortable.

As an example I am the kind of person that only holds a few coins because that is what I find to be effective for me, but you can look around in the forum and you will see people that are holding hundreds of coins and they are making a lot of money that way, so find something that suits you regardless of what other people are doing.