The majority of your steps are going to be complete steps. Thus it's logical to assume a complete step (meaning your heel comes to the floor to make full foot contact), rather than second-guessing the weight transfer of each step and preventing your heel from coming to the ground with each step.
Letting your heels down also lets your heels flow with the natural force of gravity. So since the majority of your steps are complete steps, the majority of your steps are also flowing with the natural force of gravity. Gravity pulls us downwards towards the earth’s center, so when we relax and remove tension from our steps, we allow the natural flow of gravity to bring our heels in contact with the floor.
Whether your heels are in contact with the floor or not plays a critical role in the natural state of your posture and balance. Your skeletal frame is literally stacked on top of the back part of your feet, aka your heels.
As a lead, I prefer to use any tension in my frame to lead the steps that will be the exception versus the majority. This way the majority of the dance my frame can be naturally relaxed. This relaxation also allows me to conserve energy so I can dance longer.
I remind a lot of the followers I train that it's important for followers to dance with their ears open! By open, I’m referring to listening to the pulse and rhythm of the music, and allowing the rhythm to guide your steps.
Hopefully, the lead is also leading in unison with the flow of the song’s rhythm as well.