wasn't as strict as i should've been on the timing (i basically waited for the exterior to dry for the 1st three brews), but the tea was quite forgiving and the flavour was pretty consistent. Also did not stop at 3 brews
just kept drinking on. lost count of how many after.
I wouldn't be strict about the timing in terms of seconds, but it should have a certain rhythm.
With 3-4 cups, this is the timing I learned...
* Fill the cups with hot water
* Fill the teapot (slow, drizzle kind of pour, in a circular motion around the sides of the pot)
* Pour the cups, 2 at a time, over the pot
* Pour the tea into the cups
Even though 4 infusions is traditional, if you do a fifth, pour the water into the cups after
filling the pot, and that will take care of the timing for the fifth brew. The reason for only drinking 4 infusions (as I've heard it), and waiting for a while before drinking other teas, is supposedly so that the experience ends on a high note - if you feel bad about wasting the tea leaves, brew it later in a bigger pot (sometimes I bring them with me to lunch, if I'm going somewhere I know will give me a teapot full of hot water).
This is one reason why I use at least two cups, even when brewing for myself - keeps the timing roughly the same, if I pour them one at a time.