Since it is mathematically impossible for me to make the knockout rounds due to my belated entry into this season (See everyone season 11 ), I thought I'd explain some of my own strategies and help some of you guys on the bubble, sneak in.
The two main obstacles to getting a high score are energy and D-time. Both of these essentially behave as timers. With the energy timer expiring halfway through each Gates stage. So in order to progress you need to be making great time through each stage. There are two way to accomplish this. Advancing full speed ahead increasing the scrolling and destroying enemies quickly. Advancing full speed ahead obviously is dangerous since you can't see whats ahead of you. In the early stages of the game I will take opportunities to do this after passing a wall then quickly retreat before the wall has moved off screen to give me time to react to the next obstacle. This is really only possible during stages 1 and 2 as the scrolling increases after stage 2 making it nearly impossible to use this technique afterwards (if my timer is expiring I tend to risk it on later stages without much success). At any rate you want to take all these chances you can early to help pad your timers.
The second technique is destroying enemies quickly and this is all about positioning. As for myself I like to hang around the top of the screen all the way at the back just a few lines below the lowest part of the ceiling. A lot of enemies and homing missiles will spawn at this height as well as the upper batteries, and lower batteries can not hit you here. Try to time your shot so as soon as a wall moves off screen or an enemy is destroyed the next obstacle will appear just as you get off a shot. If it's a battery or an enemy at that height, you will destroy it instantly quickly progressing you to the next obstacle. Remember, the faster an enemy is destroyed the faster you progress. Also this helps with homing missiles. Missiles are much easier to kill from above than from below. When tracking a missile from below, the missile will offset just enough for you to miss making it a hard kill. You want to drop down to take shots at missiles (unless it's the angled missile variety then you just need razor sharp reflexes.
And don't forget to grab that energy pill the second you see it. I know it's risky and I feel like a missile spawns almost every time after picking it up but you need the time. Don't hang back where it's safe and burn all that time. Gobble it up, quickly retreat, if a missile spawns do your best to swing around and shoot it down.
Hope this makes some sense and helps you guys out.
Nearly made the 4th gate on this run. D-time may be too much to overcome.