in my experience, I think it's very hard to find a doctor to shadow for 100 straight.
Scheduling doesn't always work well for both. For me it was easier to find other physicians to shadow then to keep shadowing same doctor.
I shadowed DO for 32 hours. 4 days in 2 weeks; each day 8 hours straight in the clinic. He couldn't do any more. Being in call, traveling, other duties makenit hard to schedule.
I found it even harder to shadow in the hospital since doctors I shadowed had even less structured schedules. Some days they couldn' it have me, some days were short. Then some days I couldn't come. It was stressful a bit to keep emailing each other every evening about shadowing. there were many changes and cancellations in his schedule.
So, I shadowed 6 doctors for about 20 hours each on average