Some tobacco varieties mature fairly uniformly after topping (e.g. CT Broadleaf). Others don't. While for most cigar wrapper, you really need to prime leaves at a specific degree of maturity, for cigar filler and for many Orientals, you don't have to be as picky. My determination of when to stalk harvest is based on the balance between losing the bottom leaf to deterioration vs. losing tip leaf because of marked immaturity (keeping in mind that the tip leaf will continue to mature while hanging on the stalk). Since I prefer to harvest all the stalks of a particular variety at the same time, I just eyeball the plants for maturity of the group as a whole, regardless of dates or timing or topping dates.
In terms of stalk-harvesting saving work, it really just shifts the task of stripping the leaf from summer to winter.
Bob