I have always preferred to stand at the workbench (as those who have worked alongside may be willing to attest).
But when writing (not that I do a lot of that these days), I really need to be sitting at a desk.
Nowadays, most of my work is done at the computer keyboard; I often put in two sessions a day, each usually lasting for five hours or more ... both standing at a 90 cm worktop (although I admit that 100, or even 110, would be more comfortable).
When using one of my internet PCs (like now), I sit at a computer desk ... but find that I slump down (poor posture) if I'm at it for too long.
Surely it is no secret that "the answer" to prolonged work in a fixed position (whether standing or sitting) is to take plenty of (hopefully short) breaks!