Component "burn in" times are purely subjective. Having to wait 800 hours is absolutely ridiculous! 50 or 100 hours might easily be enough time for the component to perform mighty fine. Unless a component is severely flat or lacking extension at X hours, I highly doubt you are going to be able to quantify the exact differences 100 or 200 or whatever hours later based on memory.
There are far too many attributes in the listening room, temperature, humidity, time of day, listener's mood, electrical power voltage,, etc. that can easily result in perceived changes. We all have experienced a time or two where something just did not sound right and we return another day for the magic again to be there.
One way to actually document differences would be to use a "fully-burned in" component as a reference, and do a comparison day to day, documented/detailed. This would determine if the differences are now constant or whether the additional day of burn-in time of the component under evaluation is truly "changing" quantitatively/qualitatively relative to the differences documented the day before. After a few days of no documented differences, it's time to end the "burn-in" process. To expect additional time to result in a black sheep suddenly becoming a golden unicorn at burn-in between day 33 vs. day 34 (800 hours) is silly at best. This comparitive process is far more objective than relying on personal memory of exactly how a component sounded or changed the day or days before.
When I first powered on the L6, I was very concerned about weak bass. In an hour or so, the expected low-end presence was there. This is very typical of tube products. I always turn them on an hour or so before I even sit down for serious music listening.
