Keeping them all in multiple wallets will ensure the risk of losing all your money goes down but the risk of losing some money due to forgotten/lost seeds goes up. So, really, you are trading one risk for another.
Just having multiple wallets alone does not really offer security, in fact i think it gives a false sense of security. What i mean is that if you have multiple online wallets for example, that does not reduce your risk of losing your funds, especially when all the wallets are stored in one device. What reduces the risk of losing your funds is when you use cold storage and add extra layers of security like a multisig wallet or extending your seed phrase with a passphrase.