Encourage your players to be proficient at all of the variations in Equations and On-Sets. Most of the time, players have favorite variations or ones with which they have prepared several strategies and Goals. But what happens when they don’t roll the right cubes to set that Goal? What do they do to when they don’t have the best cubes to set Goals?
Challenge them to use variations that they don’t typically use (such as Base m, Multiple of k, or GCF). At practices, choose three of those variations and make those the "Variations of the Day" where those are the only ones allowed in shakes. This forces them to learn even a few strategies with the "less liked" variations or to be able to use them when their opponents use them on the Goal. Sometimes, when forced to use a variation like upside-down each time, a player can learn to like a variation and find new ways to use it.
Another version of this is to have players create strategies that don’t use their favorite cubes (like roots or exponents). There are very powerful strategies that come from using just division signs—such as 5 / (1/3) that some players look beyond in creating their more-complex strategies.