100m at 1 lane is around 430SY. That's probably 2hrs of milling and an hour of tacking and paving, with maybe another hour or so for incidentals. So you may only get half a workday of production. For time consuming repairs, like full-depth replacement, the setup time cost may not be significant.

Keep in mind, though, you don't lose a lane of traffic. There is no need to truck in jersey barriers. You don't have to build an entire temporary detour road. You don't pay a consultant $200/hr to design a traffic control plan.

I think the real value is safety. The crew is shielded by the bridge and you have complete grade separation from traffic. That's a lot better than an orange barrel being the only thing between you and a minivan.