Seeing the extent of shoreline changes year to year, or even storm to storm I can only imagine the changes where the forces of current are even more extreme out in the rips. Most general purpose maps (like DeLorme) don't even show recent formations like the Chatham break!
As a part-time shore guide I scope the formations regularly each year. Although things are subject to change thru the season it's those first couple of outings in the spring that define the major characteristics of the flats and channels each year. I've gone as far as staking 6' green landscaping stakes on the high points on a minus tide and worked my way back on the flood. The key is to get familiar enough to look for the same features and identify changes from trip to trip.
Sandy inlets with major flow change constantly and need to be checked out on a per-visit basis as well as an extra measure of caution. The tip of Nauset in Chatham is a perfect example of this. Walking out to the crescent shaped bar was an easy venture one day and hazardous a few days later. A deep trench on the north end was an easy crossing a few days later. I wish I was there the day the guy wrestled a BFT to submission in that spot!
Although just about everything changes on Brewster flats, Monomoy, etc - one thing surprisingly remains every year - the 30' Blue Hole. I even saw a topo from the 70's showing 30' depth. Amazing piece of natural inshore structure!