MMO or MOBA mice are made for games that use many buttons. These mice give you virtually an extra keyboard. And you can tie these keys to whatever you want, including hotkeys and macros.
We use Corsair Scimitar as an example in this guide because it is cheap ($ 59.99) and has good software. We also love Razer's NAGA Trinity ($ 74.92), and named it one of our best gaming mice. The same general instructions should work for all mice, as long as you can tie their buttons.
How the mouse buttons can help
Outside the box there is not much to have extra buttons do for you directly. You have to tie the macros yourself to suit your needs. Try to think of everything that loses your time, even small things. It doesn't have to be huge, a second or two saved on something you do hundreds of times a day, spend time over and make your job much nicer.
For example, I work on a MacBook and prefer to use a mouse besides the built-in trackpad. Switching between desktops on MacOS is easy with the touch pad, but to do so while using a mouse, I would need to hold the Ctrl key and press an arrow key that would still use my right hand. So I've tied the changing desk to the left and right to 4 and 5 on the mouse's numpad, which saves me from moving my arm around so much. On a smaller scale, I do the same to switch back and forth between Chrome tabs (and any other apps that have tabs) with 1and 2 for left and right, instead of using quick command combinations or clicking the top row with the mouse.  By the way, Windows has the same type of virtual desktop swap that MacOS does, but you may not even notice if you don't know the hotkeys (Windows + Control + Arrow keys). Binding these to mouse buttons makes the Windows virtual desktop much easier to use, and will help clean up your messy mess of Windows.
Keyboard shortcut avicionados will still swear by their methods. For some apps, with both hands on the keyboard, it is much faster than using a mouse in the first place, which is something that all vim users can attest to. But on a modern system you will use a mouse at some point. It is best to get the most out and not let it slow you down, especially if you have a mouse with many buttons anyway.
Configure your mouse
Setup depends on the mouse you own and its software, but most mouse manufacturers' tools let you do similar things. Corsair's Utility Engine is very powerful and offers full macro support and multiple profiles. You can configure a button to press a number of key combinations, so the options you have are quite unlimited.
Profile switching is an extremely useful feature, since it essentially lets you nose macros behind other buttons. I have 10, 11 and 12 set to switch to different profiles, and then switch back after another button is pressed. This gives me 45 different slots to fit macros in, even though I haven't really filled them yet. You can configure different profiles for different apps and one separately for games that will leave the number buttons unaffected.
Corsair's iCUE saves the profile to the mouse so that the same button layout will remain on different computers or different operating systems, useful for dual-boot systems.
While you have lots of macros, it's cool, even if it's something as simple as using buttons 1 and 2 as the left and right arrow keys, saving you plenty of time day to day. Find what works for you and build your workflow around it.
You will quickly reach a limit on how much you can do with just restoring keyboard shortcuts. Fortunately, you can install a few extra tools to download the slack, which can drastically improve your workflow.
- AutoHotkey (Windows) – If you thought 45 nested macros were overclocked, try to have your macros Turing-complete. AutoHotkey is a wonderful scripting language centered around shortcuts and macros, but the language has been expanded over the years to be more like a full programming language. It has loops, control structures, the ability to read and write to files, move the mouse around and the ability to start executable files. You can configure your mouse buttons to launch AHK scripts or actions instantly, making it a huge upgrade over existing functionality.
- BetterTouchTool (Mac) – Exclusive to macOS, BetterTouchTool is trying to be AHK for Mac. It is much easier to use but offers support for multi-touch touchpad feedback, touch screen customization and even Siri Remote. It's a good job for MacOS.