Go check out the Navionics Webapp....that shows you all of the latest and greatest from Navionics for free, so before you spend a dime you can decide if they are right for you. With the Sonar Chart program Navionics is averaging around 20,000 updates per week. Now granted, those may not be all the lakes you fish, but it is a good example of why the free updates that come with the card are important to utilize.https://webapp.navionics.com/#boating
Or if you may have an old card, whether it be a LakeMaster, Navionics or any other brand, you can save some cash and buy the updates card. This card is the same data just gives you a price break due to already buying another card.