Help me understand how awesome WP SMUSH PRO is.

First of all, thank you so much for giving me this opportunity again to be part of this awesome community ( even if it's for just a short span of time )

I am in love WPMUDEV since long and am able to talk to you guys directly for the second time ( I think after a year) as you have rolled out an offer to give us a re-trial.

Actually, I don't need a trial to understand how amazing you guys and your services are but the problem is that I don't have money to be able to exist here for long. I left my job 2 years back and worked on my startup which is not profitable yet. I have also started few WordPress based side-projects to earn a little. I am hopeful that one day, I will have enough money to afford this awesomeness for a longer period of time.

Anyways, let's come to the question now.

I have used 'WP Smush Pro' on one of my sites and have successfully smushed 65045 images ( Wow! Isn't it great ) including thumbnails, etc. The uploaded image count is 4609. Here is the screenshot:

https://s4.postimg.org/6vfncf4n1/2017-05-26_10-21-02.jpg

Though it actually took a total of 5 days to smush these images. Reason - The process used to automatically stop even if I haven't closed the tab or without any interruption in internet connection.
Even after 5 days, I am still not able to smush last 74 images. I have tried dozens of time, but it completes automatically and then I have re-check images and start compression process. Why is it so? Is it because of the large numbers of images?

One more thing, My total saving is 358.4 MB / 18.9% with 65045 images smushed. Is this compression effective? Based on your experience with WP Smush. Is this a good optimization? Will it actually speed up my site considerably?

Thank you.