Traditional plasterers achieve perfectly flat and smooth walls with nothing more than a trowel…no sanding required.
Yes, you heard me, no sanding at all!
For years I’ve used what was readily available to achieve the “plaster” look. At this point I’ve probably applied close to 300 gallons of joint compound to give our walls the authentically vintage look of plaster. I’ve also discussed this somewhat labor intensive and messy method at length, which included the many MANY references to sanding it all smooth until my arms could sand no more.
Over the years I adopted techniques to ease the process, tools to reduce the mess, dust collection methods to keep the drywall dust from venturing into each and every nook and cranny in the house. But no matter how good I got, it was always the same: apply, sand, apply, sand, apply, sand, repeat until you cry out to the wall “I have a bad mustache and I just can’t take this any longer!”
Your situation may be different than mine, but you get the idea.