I’ve seen that there is an exact pace of changing weapons to do more harm, what is it? Because I do less harm than a friend of mine and I spam much faster

For lobber / roundabout swaps; anything above or below 7-8 swaps per second is slower.

For plane levels, there is a rhythm you have to learn. Every half second or so, switch to your bombs then switch back. You want to switch to the bombs every time their cooldown resets. The more accurate your swapping, the faster. If you swap as fast as you can, you lose a lot of damage.

Or maybe is because you are on curent pach