For commercial grows, synchronizing harvest time saves money. For home grows, that doesn't matter. Recommendations by extension services is to top the plants when 50% of the plants are showing at least one blossom, and videos of those commercial grows reflect that. For home growing, the ideal is to top each plant after the bud stalk elongates, which is usually just before its first blossom opens.
If you have a few plants that are way behind in growth, compared to the others of its variety, you can help them "catch up" in maturity by topping them at a lower leaf count.
For any videos of growing tobacco commercially, you should examine every choice and practice (and tradition) in a context of why it might be advantageous for a commercial grower to choose that method. It usually comes down to reduced cost and labor.
Bob