1. You must split your coins in 2-3 wallets, to avoid losing all your coins if they are all in one wallet. But then you don't know what types of wallets to use.
The only time I see using more than one wallet beneficial is if the other wallets serve different purposes. For example you could split your funds into "long term storage", "day to day spending", "trading". Each one needs a different type of wallet, for example the long term storage needs a solid cold storage while day to day spending can be done using a mobile wallet and for trading a hot wallet and the custodial wallet exchange accounts could be used. Obviously backup of the cold storage is the most important one that needs extra care.