Wanting to expand knowledge and understanding is an admirable quality. A mark of top sales professionals is that they never stop looking for new insights to make selling easier and more productive. That is why most of the sales books are purchased by sales people who are already successful.
This is at direct odds with people I regularly meet who are very clever people who have read a few books and think that they know it all!
After 15 years of learning about all the various aspects of sales, psychology, human behaviour, sales process, goal setting etc etc I still continue to learn. I go back and re-read or re-listen to materials. I probably listen to the Accidental Salesman recorded interviews more than anyone else!
I have a very simple outlook. If people who are very successful in sales continually invest in their own learning then there is probably something in it!
Its the small differences that can make a big difference. If you learn and apply one small nugget each week which increases your sales by just 1% then over the course of a year it will add up to over 50% and it will be a compound growth too!
When someone thinks they know it all then they miss out on more sales for less effort. That can be an expensive mistake to make.