I have been involved in carpentry for the last 30 years. During that time I have always been one to look for an easier way to do things.
Often that means coming up with my own jigs, thereby making my job easier, safer, more accurate, and less costly.
Here is a jig that I have found quite useful when installing drawer slides.
Because drawer slides can be difficult to install in a cabinet box that is already built, I made a couple of jigs to install the slides before I assembled the cabinet box. That made installation much easier and faster.
Even if you are only building one set of drawers (like a dresser or a chest) it is much easier to mount the slides on a panel that is laying flat on the workbench than it is to mount the slides on a panel that is already standing up.
So stop working against gravity and, instead, let gravity work for you.
The jigs are really easy to build with a dado blade or router with a straight bit.
Just dado a slot to hold the slide where you want it. Make 2 at the same time, so that they will line the slides up square. You can make one wide one and cut it in half to make sure that they are perfectly aligned.
I have set this particular jig up for a 36″ cabinet with four drawers (of various sizes). You will set up yours according to your needs.