Just reading posts in another thread about the Swiss cheese model promoted me to think about anchoring.
Just got back from a cruise up to the whitsundays, many of the anchorages were full by the end of the day.
Common sense would tell you to leave ample room between boats to allow for the way boats swing differently. All that seemed achieve was to invite another boat to anchor in between what you thought was a sensible distance from the next boat and you end three boats on top of each other.
Should you anchor as close to the next boat to deter that from happening. It's not always possible to pick up and move when someone anchors on top of you in a small anchorage and it happens regularly.
Last two anchorages behind Fraser Island I had it happen, both were ridiculous. One was King fisher bay. A huge anchorage but deep, 15mtrs and strong tidal currents. I left what I thought was ample room and a yacht starts to anchor inbetween us when there was no one behind me. I said to the guy as he was dropping just in front of us. "I have 60mtrs of chain out". He says 60mts, what for. I said its 15mtrs down, I thought 60 was the minimum. He moved behind but wasn't happy. WtF the difference in the dinghy ride to shore from between us to behind us would be 30 seconds.
It seems being sensible encourages other to not be sometimes.
Same as driving in traffic, leaving a sensible gap is just an invite to dive into said gap if their lane starts slowing, pretty frustrating when you're towing a load and need that space..
but yeah, quite a lot of people don't understand how an anchor actually works either, so theres that.
So many times someone has anchored over my pick. I generally assume a 5:1 ratio and if someone turns up I'll tell them I'm at 5:1 (3:1 if very good holding) but usually ignored. Then I ask them to shift when I move regardless if over my anchor or not as I usually can't see where it's at. Gold coast and Whitsundays were the worst with some very big arrogant motor boats thinking they are better. I advise those guys to hang out fenders because I'm heading off. Their choice if they comply or want to be "superior". 
I can remember anchoring off the Zoo in Athol Bight for one of the major events. All the family were aboard my fathers 1923 timber cutter with a 5' bowsprit.
We must have jagged a good holding as all those who anchored to windward, drifted back on to us. Bowsprit did its job protecting our line. Remarkable the number of power boaters who in turn asked us to move because they couldn't get a good holding.
Events like that it pays to get in early and when leaving, take your time and let the idiots go.
Steel bowsprit with chain stays seems to get respect 
. But yes it's the anchor in fronters who seem to be most entitled. A bouy on the anchor service a couple of purposes
I used to try and protect my anchor spot but in the end it got too hard and bad for my blood pressure - I would send the kids on deck or give my new neighbours a stare if they were too close. There was also the time I got cranky and moved when someone was too close to windward and I called out to the crew of the offending boat that I didn't like their seamanship. (Something very unlike my usual manner). The guy came over and we had a fine chat - he said he thought it was fine and I said it was too close but I appreciated him coming to chat.
In the end a power anchor winch and a good dinghy are great. I would wait in a less crowded part of the anchorage and then at the end of the day I would be the one who would drop the hook in the space left in the more preferred area. It is a real hassle with manual anchor setups but an electric anchor winch allowed me to move with ease and it eased my mind as well.
Anchoring yarns, Whitehaven is a lovely anchorage & chalkies is really good snorkeling but is prone to wind over tide. Our preferred MO is chalkies in the arvo drop the mooring and steam over to Whitehaven, the lark being the flotilla retrieving ground tackle @ WH & making all haste for the one recently vacated mooring ! And of course we we anchor out the back 
