If it makes anyone feel more at ease, this used to be an issue for me, but after drawing for as long as I have, including over ten years as a professional illustrator, I'm now barely affected by it.
Over time, your "muscle memory" (actually pathways in your brain, nothing to do with muscles) and the understanding of space, anatomy and light that support your drawing skills will become so reinforced from practice that it takes literally a month off to see a drop in quality big enough for most people to notice at all.
In fact, taking breaks now and then can be good to avoid reinforcing bad habits, like drawing things a certain way from memory without thinking.
Practice regularly and don't neglect spending time just thinking about why you draw things a certain way, doing studies, reading tutorials and books on art theory and looking at great artwork. Over time (and by time I mean years), you'll build up a strong foundation so that even if you take a week or two off, it'll only take a few sketches to get you limbered up and ready to draw to pro standard.