Did just this thing today? was fine until about 4:30pm then the fact it was dark outside? (what happened to the weather in the last week?) I hit the wall and felt not very productive for the last hour but before then I was fine, I was also flying J. Easily do able if you have to and besides if you turn up at 2pm to work how much later do you have to work and is it really worth it for at most 5 hours