For green teas, you want to avoid steeping them for more than 3-5 minutes or else it gets really bitter. The same goes for if you’re steeping mate.
White teas are really delicate, so if the temperature is too high, it’ll ruin the flavour.
Herbal teas need to be steeped at a higher temperature for a longer time because… well, they’re not tea leaves! It takes more to get whatever it is you’re using to release its flavour, basically.
There’s more to it, but that’s all I can remember off the top of my head.
ALLY OR ANY OF MY OTHER TEA-SAVVY BUDDIES, any input or anything to add on to what I said?
Rooibos teas should be heated at 208 degrees and steeped for about 5-6 minutes.
Blooming teas (1 ball) should be heated at 180 degrees and steeped for about 3-4 minutes, until the ball has bloomed fully.
It should also be noted that if you’re trying to make a normally hot tea into iced, you typically have to double the amount. For example, if you have a rooibos tea that would ordinarily only have a 1.5 tsp serving, for iced, you’d make it 3 tsps.