Only some selective details. Such as the easy forgotten fact that humans can strafe jump directly from one ledge to the other on ATCS, so you don't actually need fancy luci jumps or grenade jumps, and you can do it even during S1.
Some of the mistakes can be forgotten because the aliens were probably S1. Hence the absence of trappers and the fact you should place structures on walls and ceilings rather than the ground, to reduce grenade or luci damage. And we don't know for sure that the other side is not protected, it's not in the picture.
And now some explanations for those who are learning.
Clustered alien structures will be more easily affected by zone damage attacks such as luci, flamer, grenade etc. So space them apart whenever possible, and place them on walls or ceilings once you get S2 and advanced grangers.
A side note: on ATCS, it is possible to place some stuff on tilted walls even with normal granger. Experiment on devmap and see when those structures turn green.
While protecting the ramp to OM with tubes is useful, don't overdo it. Expert players will know how to avoid them anyway, and you're limiting access for your own classes (rants or normal grangers). I prefer placing just 2-3 tubes there, near the corner of the ledge, but leave the way open. You'd be surprised how often humans will prefer letting them alone and run past if they can. But they take damage that way and are easier to kill.
This is actually a good idea for tube placement. If they are scattered around and don't seem to hinder the humans too much, a lot of players will leave (some of) them alone. Only very cautious players will destroy an alien base methodically, bit by bit. Plus, they tend to focus on eggs and OM anyway.
Barricades are quite seldom useful. They are good as temporary solutions, to gain you a few extra seconds by blocking a passageway. But usually the build points are better spent on other structures. Barricades seem to be preferred by newbies because it gives them a (false) feeling of security, of "closing down" their base. An alien base should be an open and inviting trap, not a solid box.
Which brings to mind another issue about tubes. They should be placed in such a way that in order to shoot them the human needs to get close enough to get damage from them. Ideally, there should be trappers around that ensure that once the human gets there he can't leave easily.
I hope I don't need to stress how important OM and eggs are for the aliens. So the should be well protected. But at the same time, aliens have the ability to recover even after complete OM+eggs wipeout (granted, it's hard and even harder on a small map like ATCS).
Another important point: bases aren't supposed to be fixed from start to end of game. Actually, they should evolve according to stage and game situation. An alien builder is freed from the tedious task of repairing structures, and they build faster than humans. They should use that precious time to reconfigure the base when needed.
