Have to manually set date for "forever" slow mode

The workaround of picking a ridiculous date into the future indeed turns this from a problem to an inconvenience, so thank you for that.

However, my suggestion to add “Forever” to the list still stands, I think. The option is not present in the list.

If you look at the thread linked a few messages ago by @ondrej, several people including me seem to be using the feature this way, so I would think there is a legitimate argument for this use case to be included in the UI.