Is There a Method to Block Concurrent Requests From Running?

Yes. From the manager work shift, by making the processes=0 for that work shift at specific time and date.

Something to remember when creating manager work shifts that:

A. Date-specific work shifts override work shifts that do not specify a specific date.
B. Overlapping Work Shifts - Priority Levels:

1. The work shift with the more specific time period takes effect for the overlapping time period.

2. Overlapping work shifts with the same priority:

The work shift with the largest target processes takes effect.