The RR database of amateur repeaters in not complete by any means. This is because there is no FCC database to refer to. I suspect that the listing are based on information submitted to RR. Closed repeaters probably are not listed to take one example. When traveling I find the websites of clubs in my area of interest and program in that information. They will give you coverage information and times of nets etc. The ARRL Repeater Book is somewhat more helpful but some listings only say "covers area" or something unhelpful. Remember that amateur licenses are issued to individuals or clubs but not for specific frequencies as in public safety or business. RepeaterBook.com is a much better source and works with RT Systems software. I suggest that you explore that.