As a teenager, I woudl get smegma often despite properly washing penis. When masturating, I woudl first retract foreskin, let glans/skin dry, and then rub off the dead skin (aka: smegma). Then I was good to go for masturbation.
After I became semi cut, I never really got smegma anymore. My glans became fully exposed during every erection at night and ofren in underwear in day, so the dead skin cells (which do the "white" stuff in smegma) got rubbed off before they decomposed into smegma.
However, I continued to have the smegma smells. And it doesn't take long for the smell to happen after skin is brought back over head and dick placed back in underwear.
BTW, Smegma isn't a pain in the ass. It isn't painful, it is just very unpleasant sight and smell so it is a pain in the brain
Lack of smell was a huge plus of getting a full circ.