To get the most flavor and benefits out of the herbs, go ahead and put the herbs to the test and reboil them. First of all, you get to double the rounds of tea drinking for some herbs you couldn't get enough of. Second of all, you get to save more on your herbal tea blends. It's a win-win! Reboiling your tea also increases the number of servings. So if you like making your teas in big batches and saving them for later to drink throughout the day, this method is great.
I recommend doing the reboiling method on high pigmented, aromatic and thick herbs and roots like hibiscus, tila flower, sarsaparilla, clove, cinnamon, ginger, etc. I also like to re-steep herbs that leave a strong aromatic like chamomile, peppermint, and rosemary.
Here are some blends we like to reboil:
Sweet, Spice, Everything Fire Chai