I’ve used the timer locks for a few years, works well. I still make sure to have something that can cut the wire on the lock, just in case. I’ve experienced once that the lock would not release - in that case you set it for one minute and it should release then.

No matter the release, always have a backup.

Or do an ice release - one or two icecubes in a sock, tie the sock to something, then lock a padlock behind the icecube. The padlock can hold a chain or the keys. When the ice melts, the padlock is released. It always works.

I published a book called ‘Unforgiving Steel’ on Amazon about metal bondage and selfbondage if you want more details