On Some Holes, your putter value range will change to a higher range, even when the distance is within the lower range. This often results in a LONG putt if not detected. WHY does this happen...
WTR55, if you are on the fringe (not the green), the caddy will almost always give you either a 100 foot putting scale or a 50/60 foot scale.
If you are on the green, the caddy will give you a scale based on the distance from your ball to the cup. I believe (but am not 100% sure) that if your distance is within 1 foot of the end of a scale, it will move you up to the next scale. I tested this today and when I had a 18.9 foot putt, the caddy gave me my 20 foot scale. When I had a 19.3 foot putt, it gave me my 50 foot scale.
As others have said, make it part of your putt routine to always make sure you are on the scale you want. The WGT caddy is far from perfect and it cannot read your mind. It also does not take into consideration the elevation change or the green speed.