@synchromesh - It's almost always faster to use a keyboard shortcut then to have to click an icon. Especially these days, with the prevalence of wide and ultra-wide monitors. Your hands are normally already positioned on the keyboard to almost instantly hit any key or key combo. But to hit that test game icon, you have to move the mouse from one area of the screen to another, then click. It's slower. Frankly, not much slower, but it's still slower.
As a freelance artist who works in several programs, I used to be (years ago) resistant to learning keyboard shortcuts. After all, why should I when they are all (or mostly) represented as icons and menu items? But when I started to learn a few and slowly, over time, added more keyboard shortcuts to my workflow, I found I was working faster and more fluidly. So, it's always good to have a keyboard shortcut for most things you do in any app.
Now, having said that, Test Game is not something that is used that frequently (not compared to rotating an object or using the WASD keys to move about, etc.). So, I am not sure Test Game actually needs a shortcut, but it couldn't hurt to have one, me thinks.
Intel i9-10900K 5.10GHz, 64 GB RAM, Nvidia GTX 1080 ti 11GB, Windows 10 64-bit, dual monitor display