Is there a reason I can't place GND as a copper zone?

[Piotr]

@johannespfister

Is it correct that you use a 2 layer board?

My 3 cents about 2 layer boards.
Since I read those articles (from links I mentioned a moment ago) my 2 layer PCB strategy was to route 100% signal and power tracks on top with whole bottom being the continuous GND. I sometimes had to use some 0Rs to not break my GND continuity.
An example of such designed PCB I showed here:

Approaching PCB track routing for a newbie

Positioning for me is the main work in designing PCB. If each element is where it is needed than routing is simple. Till now all my PCBs are 2 layers and all of them have GND plane taking 100% of bottom layer. So except GND I design my PCBs as 1 layer. I use microcontrollers in QFP packages without thermal pad at bottom. This allows me to go with VCC under the microcontroller and go out through all corners and all VCC pins. That way GND and VCC don’t disturb my signal connections. At all digi…

Recently I started to use QFN microcontroller cases and as VCC routing as at the picture above became not possible I decided to use 4 layer PCBs as it is the only way to still have continuous GND layer.