The dead man switch is what Taproot enables.

You cand buld wallets which is controlled by multiple keys by them self or in combination.

For example you can build a wallet where your key always have access to the funds. A second key which only have access to the funds in combination with a third key. The third key have only access to the funds together with the second key, but after a block height this third key have full access alone.

The dead man switch can be constructed with MAST today there is no best practice with MAST and most likley usage will only result in losses.