Adequate coverage with CLD is 25%, but that's just adequate coverage... Would 90-100% coverage have any negative results other then time and money spent, no! Does the added CLD help, yes. Just the weight alone added to a flimsy door will help about every aspect of the speakers performance, maybe it's a marginal gain, but it's a gain. Same applies with CLD on the backside if door panels too.
Bracing, proper baffles, ect will further assist... Weakest link is the door itself. Bracing, baffles, CLD, and other treatments are all techniques that aid in woofer performance. There are many roads to take to get to a destination... This video highlights Marks way.
My way starts with the largest, thickest, most sustainable baffle I can make. Void free Baltic Birch, HDPE, Aluminum... Then go from there.