Dvds made with encore cs5 not using full 4.65gb as cs4 did

Question

The majority of my video work consists of burning DVDs of event videos that are longer than two hours. I edit the video, dynamic link over to Premiere, add a second time line with a 10 second logo video and render the DVD. And since the begining of time with CS3, these DVD images always come out to be 4.65/4.66 gb (according to OS X). Now, with CS5, changing absolutely nothing--exact same workflow--Encore is only using 4.21 gb of space. The disc info section of the build pane lists around 450mb of free space (on the particular project I'm looking at right now).
This is a significant amount of wasted space and is unacceptable. Why is this happening?

Answer 1

I was finally able to talk to someone from Adobe and they tell me that this is the expected behavior, that supposedly not all DVDs are manufactured at the correct size and this extra space is to prevent problems. Should that even be true (aren't DVD's a standard?? If it says there's 4.7gb on it doesn't than mean there's 4.7gb??) this is a STUPID decision for the following reasons:
* It doesn't show this 500mb extra space until after you render your items. Before that time, it shows all the disc space being used--1 or 2 megs free and no more
* If this is necessary then make the default disc image size 4.2gb and add it to the drop-down list of sizes. Then I can pick 4.7 if I want it.
* It doesn't even always leave 500mb. Sometimes, completely unexplicably--I'd say 10% of the time, it uses the full amount of space...like it's done since Encore v1.0. So if I manually change the disc size to 5.2 in order to get the right size image, I sometimes find that nope, Encore isn't drunk today, and I now have a 5.2gb disc image and have to start over.
It seems like every time I update my software w/ the promise of things speeding up my workflow (and other things in CS5 have), something like this pops up to F it all up and I resign myself to thinking well, I guess Adobe will fix this one day...and call it CS6 and charge me another $700 for it.