ATM Caustic Zone Length

[ic089@cleveland.Freenet.Edu (John H. Svensson)]

Pardon the newbie question which follows but to clear uo/p a seeming
discrepancy for others who may just be getting started on their first mirror:
Someone on the list referred to Berry's recommended "72 strokes" to 
parabolize from a sphere, Tex states it's about an hour's job on an 8",
certainly more than 72 strokes even at a moderate 25 per minute rate.  Who's
right here, or at least who is closer to the mark for the average polisher?
I ask because I'm using Tex and set off on about 2 , 10minute "classis/c
stroke" sessions expecting it to be about 45 minutes to be close for a 6",
my central ray to marginal ray focus images don't seem to be coming down
toward my theoretical .09 inch caustic zone.  Have I inadvertently gone
hyperbolic? TIA.  
jhs