The built in maps on the lakes I fished are not very good.
The lakeVu Ultra HD card I have a love hate relationship with.
It does seem that sometimes the map on the lake is way off, like where on the map you should be on the structure your looking for, but really your still 50ft to 200 ft off.
I have gotten into the habit to turn on Quickdraw now as soon as I leave the landing. Another thing that I found out is you should have your SD card your writing to in the same unit your viewing the maps with. The reason there is, if I am mapping with my console unit and then fishing from the bow, it does take a while for the map to refresh on the bow and sometimes seems choppy. I can reproduce the same thing with if I have both at the console.
Also another note which I found out after the fact, if you have the 2017 lakeVu chip, you need to select fishing maps and not nav maps to be able to see the contours.
After using Garmins for a year now, I do like them and really like panoptix for walleye fishing. Sonar picture is awesome. I do think their mapping is somewhat lacking, compared to what lakemaster and navonics already have with HB and Low\Navico
That is my 2 cents.