I've taken to using the bag mud. 45 minutes is a good choice. It sets up like concrete by chemical reaction and does not shrink like the bucket stuff. You can recoat before it dries. Just wait an hour or two and add a second layer.

Setting compound can be mixed stiffer and makes overhead work easier.

If mixed with the minimum amount of water to be workable it has very little shrinkage on hardening, unlike the premixed mud (that 'hardens' by just drying out).

Use Easysand if you are just starting with setting compound.

Durabond is so hard it cannot be effectively sanded.

no matter what I do,when dragging the knife to try to smoooth swath....eventually it starts o rip a a line...almost like a little stone gets on the knife and starts to drag along...I think I give up.

Thinner mud and clean/wipe the edge of the knife on every pass. Two strokes should do it. You have to use 3 or 4 knives, 4"?, 6", 9", 12". After two hours run the dry knife on the wall to get all the ridges off and do the next size.

"no matter what I do,when dragging the knife to try to smoooth swath.."

Your technique sounds bad.

The first coat for paper is just enough to make sure it completely covers the back of the tape when struck off with a 5 or 6 inch knife.

You are NOT trying to make a perfect seam, just bed the tape (above and below) and avoid large lumps, bumps, and skips.

Come back with the knife after the compound has set and shave off any significant ridges.

The next coat is applied separately to each side of the seam. The knife edge close to the middle of the seam and very close to parallel to the surface.
The edge of the seam away from the joint should have almost no compound left at all.

After setting, a clean up with the knife of any obvious ridges.

The third coat fills in defects in the first two coats mainly, leaving a seam about 12 inches wide and very smooth (paintable smooth if you are good).

If you are not very good you may need to lightly sand, and maybe even add a fourth coat.

It takes a decent amount of hand strength to apply smooth coats with any speed.
Going back over and over to the same area should be avoided.

Leave it alone till the next coat.

My technique is bad I agree. I got some fresh green lid stuff and things went a little better..it seamed smoother. Not sure why the 5g thing would not last a month. I have been using the 3 size knives. My biggest issue is dragging the knife over a long span...4+ feet....it rips a flowing notch. To correct, I end up taking the 12" knife and dragging it perpendicular...then its smooth but then I have ridges every 12 inches. When I go the propper way, it always starts to rip a notch. When things are going well...it leaves pinholes.