Not changing wheel settings is a mistake.
Not knowing what dumping and stiffness means is a fatal mistake!
I assure you this is not black magic, or even sage teachings. It's very simple:

Damping is how fast the suspension will respond to a change. To put it even more simply, the more, the stiffer the suspension will be (I recommend putting it at 3-4.8)

Stiffness is how much "weight" will be put on the springs in static. Simply put - the heavier the bot, the more you should put this parameter. You can see how bad it is if you look at the suspension in test mode. If it sags more than 90 degrees relative to the mount - everything is bad (if everything is at maximum, you need to add more wheels to distribute the load).

I advise you to test suspension behaviour on lightweight bots - you will notice the difference more on them.