It might help, but I do think that moving on regular intervals would probably have a larger impact. Personally, I find that my productivity takes a major hit when I spend the whole day at my standing desk, UNLESS I am mostly doing readings, which I do at the same pace standing as sitting. Something like calculus, statistics, graphing, those kinds of heavy-on-the-writing activities I am just much faster at when sitting.
My set up has gotten pretty elaborate: old book shelf for standing (where I do all my reading), little desk for written work (with just a kitchen chair, but I hope to upgrade someday), white board for interactive work (drawing graphs etc), and a good amount of floor space for pacing and movement. Moving between all these activities has really allowed me to prolong my concentration, and I think is beneficial for just switching it up.
I pace whenever I'm on the phone (chance to move), pace when I'm stuck on problems, do calf raises regularly (careful, easy to go overboard then not be able to touch your heel to the ground the next day, haha), do wall push-ups (little more low key in an office setting), do chair dips (the only good thing about sitting in a kitchen chair) and stretch a LOT. I can't sit still in a chair with my heels on the floor- I'm mostly cross legged, so I stretch out my sides, spine, and neck regularly.