Ritual Casting

I've been contemplating an addition to Ritual Casting of spells... I don't know what y'all will think about it, so I'm going to lay it out here and we can discuss it before we try it (if we do.)

The basics of Ritual Casting are that you can cast a prepared spell that has the Ritual tag without actually expending a spell slot, with the caveat that it adds 10 minutes to the base casting time. This means most spells take 10 minutes + 1 round, though some take longer.

The idea I have is to add another tier to Ritual Casting, where the time increases instead by 1 hour... However, you can use it to cast any spell you know with the Ritual tag, even if it's not prepared for the day. For example, you might know Comprehend Languages. With basic Ritual Casting, if you have it prepared you can cast it in 10 minutes without using a spell slot; with this change, you can cast it in an hour without using a spell slot OR having it prepared for the day.

How useful this might be to the party is debatable... I think it's far more likely to be something that is used by the world at large, but isn't super handy to the average adventurer.

Thoughts?