It can also refer to how fast a metal detector recovers from signalling a coin, telling you the information on the target, and being ready to do the same on the next target. My fisher F75 has a fast recovery time. I can swing as fast as I want and get full target information on items inches apart. Some metal detectors recover slower, so you swing slower to get all the information and see if you want to dig the target. The minelab explorer has a slower recovery time in general.
Some machines actually do better the faster you swing, and some do better the slower you swing. Recovery time is good information to know about any detector you are thinking of purchasing, or one that you own.