Higher quality actually equates to quantity as in how long it lasts. If someone's crop is low grade even though there is more of it they will smoke more of it at a time and smoke more often. If you have a smaller amount of high quality herb you will smoke less of it at a time and smoke it less often because the buzz will last longer.
If someone is a commercial grower and has customers who can only afford low grade herb then quantity would be of higher importance to the grower, but not if it is for personal consumption.
If you want quality learn about all aspects of growing before you make an attempt and make sure you can afford high quality genetics and also be able to afford a top notch setup for growing.