The whole point of RCs is not necessarily to inspire you to go, "Oh, maybe I should double-check this text" or something of that nature. It's more about training your mind to watch for things that could be out of the ordinary, to watch for things that would cause you to think that you are dreaming. I don't encourage people to time their RCs (ie. once every hour or so), but rather to find something a bit more specific to focus on.

Sometimes practicing timed RCs may cause you to do one randomly in a dream and you can become lucid from that, but to be honest, in the LDs I've had, in just about every one I'm already fairly certain that I'm dreaming before I even do an RC. I just do the RC to make sure that I am dreaming so I don't do something dangerous or stupid (like jump off of a building). That could be bad.

When you're dealing with "double take" RCs (as you put them) you can do them with a number of things. You can do it with a paper with any writing on it, with people (to see if they're still there or have changed), and it's also easy to do with a watch.

I think that the key with D-T RCs (ha, new acronym) is to find something that appears often enough in your dreams to inspire you to do an RC. Practicing with a watch IRL won't do a whole lot of good if you never look at your watch in your dreams. That doens't mean you can't develop a habit of it, but it may take more time. If you're often looking at text in your dreams, then go with that.

Long explination of my point of view, but I hope it helped.