How old are your charts?
Ralph, here are a few thoughts re: your chart questions:
1. Within U.S. waters (incl. Hawaii, Puerto Rico, USVI) you''ll find the USCG and Corps of Engineers attempt to initially establish maintainable channels and aids, and then maintain them as designed. There are exceptions to this but not so much that folks aren''t reusing waterway charts e.g. for many years with few problems.
2. Outside the U.S., things can vary considerably. Few aids and little local maintenance (Bahamas e.g.) to high-end efforts by N European countries and even first world island nations (Caymans, Bermuda to mention two).
3. While NOAA updates local charts with some frequency these days (altho'' less often than it used to), NIMA publishes updates to foreign waters charts infrequently - far more area to cover and their audience is more select (mostly ships) and their needs therefore more specific.
4. After leaving the U.S., most cruisers tend to rely on guides written for a specific area and their included chartlets, rather than nationally-published charts. E.g. NIMA''s charts of the Bahamas are worthless for cruising purposes, while Pavlidis'' and Lewis'' guides and chart books (respectively) are very accurate since they use integrated electronics packages when surveying a pass, reef cut, anchorage, etc.
5. If you rely on one or two charts for most of your sailing, staying up on changes via LNM can be helpful...but it will keep you abreast of missing aids, bridge work, etc. rather than fundamental changes in a channel, right of way, separation zone, etc.