Perhaps middle-age is creeping in, but I recall an old tier point system whereby once a new level was achieved the TPs were reset back to zero and starting over again to reach the next. For example, hit 600 for Silver, drop down to 0 and hit 1,500 to make Gold; thus the whole road to gold was 2,100 tier points.
I may well be wrong but this my recollection.
A propos, I'm on the fence with this discussion and have not made up mind.
H