I'm suspicious of ruts. When I stay in a rut too long I worry that I'm not doing things as efficiently as I could. Maybe there's some newer methods that make things faster/better/stronger. Sometimes switching doesn't make sense, and sometimes it does. But you have to think about your habits to even consider changing them. It's shark engineering - keep up with the tools or you'll die!
To evaluate my habits, I'll grab a friend who's new to the codebase and explain what's going on.
For example, this is a recent one (a good habit):
Me: "Run bundle install to grab all the dependencies"
Him: "What is bundle install do?"
Me: "Bundler is a Rails 3 utility that allows you to specify all the gems your project depends on and just install them as you need them."
Him: "Oh, that's pretty cool. Saves discovering dependencies manually or installing them weirdly."
Or another recent one (neutral, this time):
Me: "Yup, we're using rspec here"
Him: "Why rspec?"
Me: "Well, it's in Rails core so there's not much to install, and the feature set is broad enough I haven't found much I can't do yet."
Him: "Oh, well, okay."
And a third (oops - a bad one):
Me: "I'm loading these with a rake task."
Him: "That's seed data, right? Why not use seeds.rb?"
Me: "Well, I taught the person providing the data how to write yaml so it's easy."
Him: "Sure, but seeds.rb can run any Ruby, so you can load the yaml from there, and then a new developer will be able to use the standard method."
This was a bad practice - and I fixed it. He was right, after all.
The point here is that I'm explaining my practices to a newbie - someone who doesn't know the code but who is an engineer. That innocent question - "Why?" - forces me to revisit a habit and to justify it. If it's good, the habit survives. If it's bad, the habit generally doesn't survive the explanation - and then I know to change it.
So if you're worried about habits, find someone and start explaining yourself - it's amazing what you can learn.