I find Space Sniffer http://www.uderzo.it/main_products/space_sniffer/ to be a much better visualisation. It updates in near real-time. If you have lots of copy/move ops going in background, you will see those dirs blinking rectangles growing/shirking in Space Sniffer.
I used Space Sniffer for a very long time, but looked for alternatives because it crashes somewhat regularly and is generally a bit of a resource hog.
Since trying WizTree I don't think I'll ever go back, it's so much faster, hasn't crashed once on me, and the visualizations are completely adequate for me to be able to see where space is being used.
Also, SpaceSniffer is the only tool of all the popular ones that correctly accounts the size of files with NTFS compression, accurately accounts for directory junctions and links (by not counting them) and NTFS alternate data streams.
I really like the visualization, the functionality to watch live file access is so freaking cool. It's a bit slow though, no? After using something like WizTree, it's hard to go to something that needs minutes to finish scanning. I do wonder what kind of a performance impact it has.
To me, this is a clone of (now dead) Space Monger https://www.portablefreeware.com/index.php?id=150