A ride op has no control over how fast a ride goes. A roller coaster is all based upon physics, and no controls can change that. As for the flow, I'm not really sure what you mean, but if the ride op and crew are slow at loading and unloading trains that kinnda relates to flow so yeah I guess they can control that. As far as better with time goes...I don't really think there's an answer to that, some get better, some get worse, some are just bad from the start (any Vekoma LOL). Like for example look at some of the coasters that have sustained their popularity throughout time, Ex. The Beast, that ride is still very popular despite being around 35 years old. Well thats all I got until next time....