Multiple mixes of a song is a technique that I've developed over the many years of my career. Music tends to unfold differently every time you approach a mix. If you're using a program that allows you to save or save as multiple times, such as ProTools or logic, it's not a bad idea to try a new mix even if you think you nailed it the first time.

Here's how I like to set up my sessions. After I record, I like to save the session as just a raw track that hasn't been mixed. Then 'save as' the name of the track_mix1. This way I have a template to go back to when I want to create a new mix. You can repeat this process as many times as you like. I usually tend to think at least three mixes is a good reference point to determine whether or not you like a mix. Sometimes it's a good idea to try up to 10 mixes.

Try this, set up a timer and give yourself a time limit for the mix. Anywhere between 10 to 15 minutes should be enough time to get a good rough mix. When the timer goes off, save your mix session, close it, & open a new session.
After you feel that you've made enough versions of the mix, go back and review each of the mixes. You can bounce each of the mixes down as an MP3 file and put them on your phone or MP3 player. Then go for a run, take a drive, or head over to a friend's house and listen to your mixes outside of the studio. This will give you a reference point as to which mix is probably the best and/or if a few mixes should be worked on and handed to a client for review.

Try this technique on your next mix and see what happens. You may be surprised that the third or fourth mix is actually the one that you wind up keeping.