it depends very much on the strain as to whether topping increases yield.
For example it is well known that Blueberry yields better when topped, whereas something like Chronic does not.
so it is best that you read up on your strains to see how they react.
in my opinion it is always worth topping one or two of the plants just to see how they react to topping for future reference.
topping usually adds a week to the growing period each time it is carried out.
in the pic you can see the difference topping can make. the plant on the left has been topped and it is apparent that it has 3 or 4 times the size bud the other one has. Strain is Buzzberry (bubblicious x blueberry).