Supervisors telling people to go faster is the way of life around my hub. Most of the time it is directed at people that are slacking, but it also used when the occasional regional/district manager walks by.
A lot of the workers take this personally, but it is generally just the supervisor doing their job. Granted, occasionally they you will come across the power tripping supervisor. Always remember, that once you are union, you can make their job hell a lot easier than they. Not everyone is going to like their boss, but shrugging off comments like "Go faster" can certainly go a long way to not stabbing them in the parking lot after shift.
As for doing 200+ at day ten, you are doing a good job. Keep your misloads down and your tiers pretty, and you definitely have a spot in the business.