First layer wallet - 20%
Second layer - 30%
Third layer - 50%

This is what im doing similar to yours on which i do make out partition on my coins and this isnt only limited on Bitcoin but also
into other altcoins as well on which i do make out that kind of dividing so that i wont really be losing it all once i  would be hacked or some exploit or do make out some mistakes.
It wont really be that hurting that much if ever there's some accident since we know that internet connected devices are really that always prone to these things.