No till will work anywhere....What happens when you till a spot that was never tilled? ...Quickly, weeds begin to grow, because you've taken the natural cover off and destroyed the ecosystem. The weeds are a "protector" to provide covering until the natural ecosystem can be restored. You don't till in a no-till garden, you don't have to dig out any dirt...just start building on top of the existing dirt. Every where in every climate the surface is made up of layers, just start layering, compost or leaves or hay or wood chips or grass clippings, etc. Think about how you make compost...just by piling up leaves, grass clippings, paper, spent garden plants, etc. and it's layered...then turns into beautiful rich compost. Study, research the no-till way and deprogram your thinking...it will work, they even use it in the desert.
maybe your using big thick woodchips as mulch when you should using more like straw or leaves? something that will break down quicker and rebuild your soil faster. so you've till'ed in garden soil + compost and added mulch ontop every year or so? maybe... each time you till in compost you reset any progress you had made.
question... each year your you should add some compost ontop, correct? so you move the mulch aside and add the compost? or just throw compost ontop of the mulch and re-mulch?
I dig or not depending on various factors. I am a big fan of no till soil building techniques. I mulch with any organic mulch that I have at hand. Woodchips, straw, hay, grass clippings or even partly or fully ready compost. Normally I strim and leave the cuttings for a few days to dry out and then use them as mulch.