Everything is a very simple small tool and it does its job perfectly. It's searches for files and folders and get instant. I prefer it over the built-in Windows search. It's super fast and it works in real time. If a software is creating new files, I can see what's being created in real time. For example I can know which files are being created and deleted during an installation.
I use it mostly to locate files. There are many times when I forget where a certain file is located or I don't remember the full name of a file. Everything helps me find it in seconds using wildcards ore regular expressions. I can sort by file name or date or size and pinpoint which file I am interested in. I open different files many times during the day and instead of wading through folders in the open file dialog, I locate the file using Everything and right-click and copy its full path and paste in the dialog. Save me a few seconds. Using tools to shave seconds from every operation during the day adds up a lot. Don't underestimate the time savings. I always seek to be highly productive, even in the mundane daily tasks.
Everything also helps me locate duplicate files. For example when I am searching for a certain file and instantly notice I have more than one copy of it. It helps me also troubleshoot issues when a piece of software is actually using the wrong version or wrong location of a file.
It's a tool which is useful in ever increasing disk drive sizes and having potentially millions of files scattered all over the place.