Two should be enough in my opinion. One of storing and one for recovering in case something happens to the first device.
Don't use wallets like Jaxx and Exodus, they are not open source, you never know what's going behind the scenes and If they have access to your funds or not.
Store everything in one device, write the seed down in multiple pieces of papers and hide them in different locations. If the hardware wallet gets lose or damaged, you could use the seed to recover your coins.
Yes, if I had such an amount I would hold it on different resources partly, of course it is better to use for this the separate device that is not used for different things like Internet or social networks. It is better not to keep the information about your keys or something like that on your gadgets at all and be extremelly attentive while trading. The security of your gadget should be strong enough and it is better to pass through the authentification.