This AppleScript "Open Applications folder" opens a Finder window for the "Applications" directory in a fixed size. The Finder sometimes "suffers" from amnesia regarding to its window sizes.
Just put this compiled script into the dock and you have it at hand quickly.
Alternatively I wrote a service which can be installed easily and assigned a keyboard shortcut to execute this code (when the finder is topmost application, just by clicking into the dock for example).
Developed and tested...