Hi Pad, I would say 2-6 weeks the most on the NXT and about 8-12 weeks on the #20, so after every other wash layer a new coat of NXT if you like. You can also go with BFWD and top it with Collinite paste wax to get about 6 months of protection on your ride. To answer your question, yes a sealant will last longer but with Collinite paste wax it will almost last just as a sealant.
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