as in adjusting it had minimal if any noticable effect on shifting assuming all other factors (cable tension, chain length primarily) were correctly set. The maximum adjustment possible with the screw was so small that in his experience adjustments did not generally make a difference. I'll take the word of folks here (well biked, operator, etc) that smallest possible gap between pulley and cogs makes shifting better but I am not sensitive enough a rider to notice the difference a couple of mills would make.
Seems like if you can adjust to min gap and still have adjustment range then it is clearly doing something right? As in if you back out the b-screw even farther then you won't be able to shift into the large cog at all. That is the main purpose of the b-screw. On shimano setups with the pivoting upper cage mount this is less of an issue, with sram its a lot more noticeable since the cage doesn't move substantially.