Diversification is always good and that is the reason for holding more than one altcoin, by this you can't make a loss at once if you really did research before buying in that same vein it is adviced not to put all your holding in one wallet.
Holding multiple coins can give a decent return on the investment if the market conditions meet the essential requirements. Without diversification making right investment looks hard to me.
the current condition of the coin is not improving. because prices are increasingly unstable. so investing now is quite troubling. the problem is that investment is now quite different from before. if in the past investment always gets quite high profits, while now the benefits are difficult to obtain.