I recently got a Zeitwerk back from servicing. It hadn't been serviced since 2013. I finally sent it in because I noticed it was gradually running more slowly over the past 4-5 years.
After getting it back, I was reminded about how much I love winding this watch -- hearing every distinct click. BUT that mainspring definitely doesn't let you forget that it's "Zeitwerk day," and you're certainly not the first person to find the stiffness annoying.
What about selling your watch and purchasing a newer version with a power reserve that's twice as long? You might've already considered that possibility and ruled it out, as it's not the best compromise, but figured I'd mention it.