Generally speaking how many times can one steep loose leaf tea?
It depends on the tea and the brewing parameters, the proportion of leaf to water that helps determine brewing time (although number of infusions relates more to the latter, how long the leaves are in water, and other conditions like temperature can be a factor). Of course this is a reference to Gongfu brewing versus Western brewing, the latter using a proportion of something like a teaspoon of tea to a cup of water, the former a much higher ratio and shorter steeping times, between a few seconds and as many as 30 seconds to a minute. So it all just depends.
Assuming Western brewing, two or three infusions sort of works as a starting point. That does lead back to different kinds of tea brewing differently, since some end up making more tea. Black teas brew out relatively faster, and some green teas or oolongs can go longer. Pu’er typically brews a lot of tea using a comparable amount of leaf, but then drinking it lighter might be more conventional, and it wouldn’t be typical to prepare that type using a Western-style brewing approach.
Whole leaf teas would brew slower and make more tea, but I personally don’t end up drinking much ground up CTC tea, lower quality machine processed teas, and it’s almost better if that factor never even comes up. Better teas keep making decent tea longer, so that completely brewing them out would be more desirable. With lower quality teas it might make more sense to brew them a couple times and toss the leaves, whole leaf or not.