Foot patterns are just the tip of the iceberg when learning to dance. Don't get caught in the trap of just learning patterns (This just makes you an incomplete dancer). I have seen people that know many patterns but can't dance any of them. I have also seen dancers that have danced for years and don't know there is a lot more that can be done between the steps.
In my opinion the quality of movement of the two-headed four-legged animal is much more important than the number of patterns that you know. What happens between the steps is the most difficult to learn, but the most rewarding in terms of feeling and oneness.
Most dances have box step patterns. If you learn only foot patterns, all of the boxes will look and feel the same. Footwork makes a difference in the feeling (Latin/Smooth). Timing makes a difference (slows/quicks). The way you move makes a difference: smooth/even -foxtrot; powerful/staccato - tango; rise/fall - waltz; flat with sway - Viennese waltz; slow, smooth, with slip pivots - bolero; Latin motion - rhythm dances, etc. Each dance has a unique look and feeling. It's own character.
A lady would rather dance a single pattern that has the feeling of the dance and oness of movement for a whole song, rather than be dragged around the floor doing 40 different mechanical patterns. Partnership dancing is all about the feeling of a single entity (the two-headed four-legged animal) using the character of the dance to move to the music.
In addition to the character of the dance, you have all the aspects of partnership, lead and follow, connection, continuation of movement, exchange of power, etc. As you can see there is a lot happening between the steps. Learn a few basic foot patterns and how to dance them. Now, as you add new patterns, the dancing between the steps will automatically be in the new patterns. It is much more difficult to go back and add the dancing between the steps to a lot of previously learned patterns.
A dance master told me: "You have to decide how you want your dancing to feel". It took me a long time to figure out what that statement meant. I though there was only one correct way to dance. There are many ways to dance. For example, a lot of dancers with jazz dancing backgrounds evolve into a method that is basically two people dancing patterns and just happen to be touching each other. There is less lead and follow involved in this method of dancing.
I prefer a method where each partner becomes one half of a single unit. That unit is a two-headed four-legged animal. The leader has to know as much about his partner's movement as he does about his own in order to have an effective and obvious lead. He dances his partners every footstep. His partner doesn't just get pushed around the floor; she participates in the lead and in supplying power. It truly is two halves of a single entity participating in the movement of the dance. This method squeezes out every bit of feeling possible. I like to dance the extremes of all movements because that is where the feeling is the greatest. . An example would be extreme rise and fall in waltz (not just a token effort). It does, however, take more skill and strength to dance the extremes. The "oneness" and "feeling" created is truly remarkable.
I tell my students: "There is no wrong in dancing as long as you are having fun and no one gets hurt". However, the more you understand how partnership dancing works the more enjoyable it will be. You have to decide how you want your dancing to feel and how much effort you want to spend to develop your dancing. This is why ballroom dancers don't all look like a bunch of clones on the dance floor. Each one is unique in style and movement.