To create banner ads faster in Photoshop, with all allowed dimensions in Google Adwords, group banner ads according to their shapes, create the bigger banner first, and then reduce it progressively. Follow these steps to save time in the banner ads creation process:
1) Download this collection of banner ads templates for Adwords in Photoshop.
2) Take a look at this scheme, since we're creating the banner ads in this order:
Square: 336x280, 300x250, 250x250, 200x200
Horizontal rectangle: 970x250, 970x90, 728x90, 468x60, 320x100, 320x50
Vertical rectangle: 300x1050, 300x600, (240x400), (160x600, 120x600)
3) Open the first template (336x280) of the "Square" group and create the first banner ad.
4) Open the second template (300x250).
5) Go back to the first banner ad. Select all layers, click on "Duplicate layers", and select the new file as destination.
6) All contents have been copied. Now select all layers, do Control + T (Free Transform), and adjust them to adapt them to the new template:
7) Repeat the process for the other "Square" banner ads, in order. Once finished, continue with the remaining groups.