I use a couple of different reels with counters and none of them are accurate. After I load them up with line, I check the counter at different distances to see how the counter is working. I measure at 30 ft, 50 ft, 70 ft and 100 ft.
I have one Okuma that is off by 25 ft for every 50 ft of line out, meaning that at 50 ft the counter is reading 75 ft and at 100 ft it reads 150 ft, etc... It does make a difference on the amount of line you put on the spool and near full is best. I check mine any time I strip off or add on a large amount of line.
It is frustrating thinking you are jigging at 50 ft where the fish are at on the sonar and actually jigging at 30 ft where there are no fish at all.