Don't get me wrong - these make my Yoga mat smell pretty awesome (which makes it feel clean, even if I'm not 100% sure it is). The amazing scent and antibacterial properties are great for Yoga studios.
That said, I always bring and use my own mat, which I wash at home in gentle detergent on a gentle cycle in the washing machine (and hang dry). Mats are also made to be antimicrobial, so unless I forget my own mat at home, this is a totally unnecessary step for me except for the lovely fragrance.
If you're using your own mat (as opposed to a borrowed studio mat), I recommend making your own essential oil spray at home if you like the scent. And really, the lavender and tea tree fragrance is kind of worth it. ;)