I've done a little research into this and found that tea is not all we think it is.
Firstly, tea bags do not contain tea leaves but tea dust. This is very important, yes, they are convenient but there is a whole world of problems when dealing with this stuff. Open any tea bag and you will find microscopic motes of brown dust, these are produced by the transportation of tea in crates from all over the world to Britain, as the tea settled and got knocked around, it produced this dust and it was thrown away years ago, as tea strainers wouldn't strain it, most producers would also include dust as it is part of the production process of tea leaf when cut and dried. But someone came up with the brilliant idea of bags so we are now here today drinking tea from dust that would normally be thrown in the river.
Secondly, we should be aware of the technical manifestations of dust as compared to leaf. There is a considerable amount of surface area with tea dust relative with leaf, much more and the effect of steeping tea dust is going to allow it to release its contents much quicker and fuller. The tea bush in its natural state stores fluoride in its leaves and of course has insecticide, herbicide, fungicide and pesticides sprayed all over it in the course of its growth and harvest.
Thirdly, making tea in a mug with a tea bag is a delicate timing procedure, no small margins for error here, if you leave it too long it becomes stewed, to early and its almost flavourless.
Here is what I do and its based on the Chinese way of making tea.
1st, you have to wake the tea up and then wash it, thats before you even brew it. After making it in this way you can have several pots of tea using the same brew. But we are not making Chinese green tea, so to get rid of the quick release of tannins, fluoride, ++icides from tea bags, just put a small amount of boiling water into the mug with the bag, swirl it around for 3-4 secs, and throw the water away, yes, throw it away, its of no use to you and its contains most of the horrible stuff you don't want to drink. Pour over more boiling water and you can now leave it for as long as you wish, you will not end up with stewed tea, what you will end up with though is a mug of tea that tastes more mellow with all the flavours that were present when it was a leaf tea.
Try it, its doesn't take much longer, you will be surprised at how much difference the tea tastes and you will have more time to brew it without the small margins for error normally associated with tea bags.
If you use bags in a pot, do the same thing with however many bags you use, throw the initial water away after 3/4 secs and continue brewing as normal, but if you are like my wife and use just one bag per pot, then you may lose some flavour as it needs more time to brew and is diluted enough already. I'd always use at least two bags minimum using the above recipe.
PS, I have seen over a number of years that tea bags have become "some" dust to "more" dust to now "all" dust. They used to contain quite a lot of small cut leaf and a little dust, but now its just plain dust so we are in fact drinking enormous amounts of tea that contains a lot of undesirable additives.
If you go out and buy large leaf loose tea, you'll notice straight away how much difference there is, its a much more intense and expansive flavour but I'm afraid we've been brought up on this inferior tea so much that some people don't like real tea any more, which is a shame.