My blog has been online for several years and I've specifically chosen a host that doesn't offer "unlimited" plans to avoid "over-sold" servers and performance issues caused by load balancing problems.
So in my case, the alternate size image bloat problem had become quite a significant problem after a few years.
With hundreds of posts already published, each with their own set of images, it was simply not feasible trying to figure out which re-sized images were not being used.
Dynamic Image Resizer solved this daunting problem by simply allowing me to mass delete all the alternate size images that were created by WordPress.
Since this plugin generates alternate sized images on demand, I didn't have to worry about breaking any existing image links anywhere in the blog--- either on the public front-end or administration back-end!
Dynamic Image Resizer isn't useful for just long-lived blogs. It's great to have if you're experimenting between different themes that may have their own respective image size requirements, or you haven't decided which alternate image sizes would be most useful to you.
Dynamic Image Resizer allows you to easily and quickly clear out the image bloat and unused resized images while avoiding the creation of broken image links.
I highly recommend this plugin!