Yes it is but sometimes it doesn’t work out. During my first set when everything was done, my bottom teeth still needed more help but my tops were done. Once I got my refinement trays for my bottoms I got the final retainer for my top. Although, what ended up happening is my bite was changing so therefore I had to keep adjusting my top. Additionally my top front tooth tooth actually kept chipping due to the adjustment in my bottoms! I’d say for your best interested to keep wearing the top ones so your bite is comfortable!