I consistantly land pretty fast using the "fist high" method. It's hard to explain without physically showing someone, but:
I stay away from the orbit line as long as possible. If my target is on the other side of the planet I NEVER enter orbit before making my descent approach. It slows you down significantly.
When your target area comes into view (solid line instead of hashed) you have to imagine your CMDR is holding his/her fist up to the left/right side of the canopy at eye level. Left fist if you're approaching from the left side, right fist if approaching from the right side. Without moving your fist, line it up with your target and begin your decent as soon as your fist covers the target area... Right at the target. Once you enter orbit, if you've done it right, you should be at (roughly) a 45 degree angle towards the target area (sometimes minor adjustments will have to be made if you're coming in a little too steep). It's very fast compared to riding the "blue zone" near orbit. Fighter pilots use the term "I got fist" or "fist high" irl on bombing runs because it's a quick, effective descent at an optimal angle. I watched C.W. Lemoine do it in DCS and I used "fist high" in ED to approach planetary landings afterward, and it works so good it's my go-to method for circumnavigating a planet and approach to target.
Likewise, when taking off and your destination is obscured, never use the blue zone. It sounds cool but wastes tons of time. It's better to just fly 90 degrees out until your completely out of orbit and fly around (avoid) the planet in SC.
