There's gotta be a dozen threads on this. The major issue isn't how many rounds you shoot, it's how fast you shoot. High rates of fire (mag dumps or rapid fire) speed up erosion of the barrel throat of unplated barrels. The $40 bucks up front for chrome is much cheaper than a new barrel down the road. If you like rapid fire, it can be a short drive.
The US Army match team uses plated barrels for all rapid fire matches (possibly for everything), they've found no significant difference in accuracy but significant differences in service life.