ITA with Dunster ... consider the ergonomics of your setup.
Everything should be at 90° angles ... back to legs at the hips, legs at the knees, elbows 90 ° with arms on the sewing surface without shrugging/raising shoulders.
I use a rolling adjustable rolling draftsman's chair including adjustable arms ... it's lowest starts at the highest of a typical office chair.
When I am straight sewing, I work at one height ... and I raise it up a tad when I am FMQ or SITD quilting.
And when I got to sewing classes, most the ergnomics are horrible and I could not last a day ... so I take along chair pads to get my chair to a better height, or sit with two chairs stacked.