We found the trick to the Natures Miracle is to massage it in really well, then let is sit for at least 10 minutes or more and let it do it's stuff before you wash it out. The longer it sits the better it works. If you can distract your pup with a kong and an on again off again massage in the tub over 20-30 minutes it definitely works! If you rinse/wash out too soon the enzyme doesn't have a chance to do its thing. And repeats definitely help, three washes is our average.
The skunk den across the street from us has a litter of baby skunks every year, and the baby skunks don't learn to control their spray until they age a bit. It's like a skunk war zone until they're three or four months old, every dog on our street is a target and we are all old pros at midnight skunk baths!