I have recently let the sign in sheet slide from my routine, but that's more because I've been working on small shows with small casts of 2 people and haven't needed it. Especially when the venue the show is performed in requires the cast to walk through the house before going to the dressing rooms, it worked perfectly fine to have them visually check in with me on arrival.
We had the sign in sheets while I was on tour, but they were basically pointless. The cast was checked in by the company manager when they got on the bus, and I performed a head count when they arrived to make sure the company manager didn't mess up (by the time the cast would have gotten to the call board, the bus driver would already be gone and we'd have no easy way of picking up a straggling actor we miscounted). We still hung it up every venue, but the cast took to the sign in sheet as a graffiti board instead of useful things....like signing in.
The only time they were necessary were in cities where the hotel was close enough to the venue we canceled the bus transportation to the venue and the cast walked. And like Matt and Dee said, the cast was not trained well and didn't sign in and we had to go hunt them down at half hour.