Sounds like a Zone-CLV strategy, you may even see 4 variations in an 8x burn
1. 4x region
2. 6x region
3. 8x region
4. unburned area
Some drives may start with 6x, but it is not possible to spin the media fast enough to get to 8x at the start.
It's also possible for the drive to downshift from the highest speed to keep the error rate from climbing toward the end, but most don't - even though it would probably be better if they did - but then, it would be better if they got a good burn, then made it fast, than a fast burn, then try and make it good!