Got to kid Boris a little--experience--you can keep doing the same thing wrong over and over again. Hopefully as you learn an art you improve... and master it. Certainly experience (as is science) is important, but I have seen some very experienced boaters who have not been able to anchor successfully--partly because they did not use the right gear, partly because they didn't use enough scope and occasionally I still see someone throw an anchor!
Let me add a little more about what I consider the "art" of anchoring. Yes, part is choosing the correct anchor. But look at the shore line for clues--was there a quarry there (as there was in Frey's harbor? Was there a logging operation (sunken logs and cables in the bottom)? What do the formations on the edges look like (ball bearing anchorage, solid rock, sand)? Can you see grass or kelp? How and where are the other boats lying--and what type of tackle are they using...,or not using? What is the wind now, and how will the surface allow changes later in the day? As the anchor touches the bottom, how does it feel? After you put out 3 to one scope, and pull on the anchor, is it setting? Let back to the 7:1, even if you may lay on shorter scope later. The lest goes on.
Yes, for anchoring you have to know a number of things, including both the bottom type (and that is why occasionally an old lead line with a hollowed out bottom historically "armed" with tallow, some waterproof grease works well in todays world, to sample the bottom.
I cruised full time for over 8 years with a 60 to 70 LB CQR as the primary anchor and it set well 95% of the time. At other times items became impaled on its point--a mason jar, a diaper, a complete Bimini top, tree limbs, and it drug in soft mud, as well brought up chunks of cohesive mud, as it broke free. I had to dive and set on occasion by cutting away the heavy grass roots with a hatchet or machete. I carried the CQR on mostly chain, plus a Danforth (40 to 70 lbs) on 50 feet of chain, plus rode, and a Fisherman 70 lb on the ready--because if one did not set, and we would determine why, another anchor was ready to go. Not practical for the C Dory.
We have found that the Mason Supreme sets well in the sea grass of the Gulf Coast where the CQR would not set well. I don't agree that the Manson Supreme is the same as a plow. It is classified as one of the shovel type along with the Ronca, Spade etc. I try to avoid kelp at the channel Islands, since I have never been secure with a set in Kelp, in my many trips there. I suspect you mean Fry's--not Friday Harbor at Santa Cruz...Fry's is a narrow harbor which in my experience is crowded with 3 to 4 boats. Most of my anchoring--and I have anchored over 1000 nights in Southern Calif. thru the years--was with Danforth Anchors from 1946 thru 1992 when I left.
But in Anchoring we all have our opinions based on our experience..