Big wall anchors: have "links"
Here’s a classic beginner mistake when making a big wall anchor. (How do I know this? My partner and I manage to do it multiple times on our first wall!)
You clove hitch the rope into the anchor, and then clip something else into the carabiner closer to the gate; let's say there's a 100 kg haul bag on the purple sling. (Sidenote, best practice is to use a docking cord for your haul bag rather than a static sling.)
So far so good . . . except when you need to untie that clove hitch. Good luck unclipping that past the loaded sling. I remember having to actually untie the end of the rope to decluster something similar to the left photo. You do NOT want to be doing this! It's frustrating and a big time waster.
It's also dangerous. Having several things loaded on the master carabiner, and then having to open that carabiner to remove one of them, is risky. Keep that gate closed whenever possible!
A solution: try to rig anchors more like the photo on the right. Avoid tying hitches and clipping slings directly into the master point carabiner, and instead add a “link” (usually a locking carabiner) to everything clipped to the master point.
Short on locking carabiners? Of course you are, that always happens on a big wall. Try a cheapskate locker; a standard carabiner with some athletic tape wrapped around the gate.
Adding “links” makes it much easier to unclip things when another part of the anchor is under load. Pretty simple concept, right? But, it's very easy to screw up, because the anchor is busy, you’re mentally a bit stressed, and you have large static loads like haul bags.
A related big wall anchor concept is known as “last in, first out”. To put it another way, the last thing that gets clipped to a master point should be the first thing that gets unclipped when you're breaking down the anchor.
(The same concept can also apply to a standard anchor, but it's usually not as important to follow. Real live humans can see the problem, clip into another part of the anchor while something gets declustered for a moment, and then re-clip. Much different and easier to solve than the dead weight of a haul bag.)
Here's another great option for a big wall masterpoint: the Grivel Vlad. It's a combination locking carabiner and rigging plate. Here's a detailed article about this cool piece of gear.