There are a few things to consider on this subject.
First these are called travel trailers. Meant to be easily moved from place to place, unlike mobile homes which are rarely moved. So some compromises must be made taking into consideration speed/ease of use and stability. The more stable, the less easy/fast it is to deploy.
Everyone needs to decide for themselves just how much effort they want to put into setup/teardown vs. how stable they want it... The same approach will not be for everyone.
As I mentioned already, the electric stabilizers that are becoming common today, do have a very big advantage in one aspect. It is impossible to rack the frame. Racking the frame results from unequal pressure on the jacks. This commonly causes doors to stick, or not latch due to the door openings being forced out of square from the frame racking. In severe cases, it could possibly cause the TT to be damaged. So racking needs to be avoided. The disadvantage is some loss in stability due to the pivoting and internal sliding that the jack does to accomplish the equal pressure at all times.
With the manual (or power) scissors jacks that many TTs came with, racking easily happens.
Part of the problem is the way they are designed.
They are sometimes called QTG (quick to ground) jacks. When you first start to extend them, each turn of the screw extends them a lot, with each sucessive turn, the extension becomes less. when close to full extension, a turn barely makes the jack any longer at all.
This is a great feature, if you understand the positives and negatives. The jack can be extended quickly, and as it nears the ground, it slows down, but because the effective gear ratio is changing with every turn, you now are able to easily get more force to the ground. This is a good thing. But it can also mean that if the jacks are extended different lengths when they are deployed on the ground, that it is VERY easy to have unequal pressure on them. You cannot simply add a turn to all of them after they touch the ground, as each jack can extend different amounts, causing the frame to be racked.
You cannot go by feel either, as the shorter extended jacks will have a taller effective gear ratio, and feel like they are putting more force to the ground than the jacks that ended up being taller,
and thus have a shorter effective gear ratio.
And then there is the ground settling issue.
Depending are your camping style, this can be a big issue or a small one. For where I camp, it is not unusual to have the jacks settle at very different rates. Add some rain and it gets worse. On my previous TT with the manual scissors jacks, I would have to make frequent adjustments to the jacks to keep the doors working right.
On my present TT with the electric jacks, the doors always work right. Settling occurs but the jacks maintain equal pressure. The result is more TT movement. It is quickly fixed with a tap of the jack buttons. For my usage, it is the best system going. I did make a change in adding two manual jacks just forward of the wheels to control the frame bounce. I have found that they are also handy for fine tuning my side to side level.
If I am going to be camped a while, I will also add my homemade wheel chocks.
While this system is not rock solid, it is an acceptable compromise for me, between ease of use, and stability.
YMMV
