I use Musher's Secret but I use it mainly in the winter to protect my dogs feet from the road salt that our city puts out on the roads/sidewalks.
When I use it in the winter, I put it on his paws before we go out for a walk and just the one application is enough to last the whole walk. Without the Musher's Secret, or some other kind of paw protection, the road salt causes him to limp. But one application of Musher's Secret right before our walk seems to be enough because then he can get through our usual 30 - 45 minute walk without limping.
From my understanding, the wax kind of soaks into the paws. So I'm not really sure if dirt would effect it at all. Even though it is clear, I can tell when the Musher's Secret is still on my dogs paws. It makes the pads of his paws have kind of a shiny/wet look to them.
On the Musher's Secret website
in the FAQ section they say this...
How often should I use Musher's Secret?
It depends on the activity level of your dog.
Mushers will "walk off"
in about a week.
In snowy conditions,
I use it 2-3 times a week
(we walk 2 miles a day)
So according to that I probably overdo it putting it on before each walk. But it's non-toxic and safe even if your dog licks it off, so I don't see any harm in putting it on more often. I have a 200 gram jar that I've had for over a year and it's not even half way gone yet, so it lasts a good amount of time even if you use it a lot. You don't need to put a ton of it on their paws for it to work
Just one thing I recommend is that I always put it on right before a walk and then take my dog out. That way he doesn't have the opportunity to lick it off or lay down and get the wax in his fur. Also, if you have slippery flooring the wax on their paws can sometimes make them slide around a bit for awhile until it fully soaks into their paws, just something to be aware of.