Different customers works with different work hours in different period of time. Unfortunately, we don't have any work hours that are bounded to the customer. We do have Work Hours template that can be attached to a customer (Service Account) but it doesn't define the customer's operating hours i.e. doesn't control when a job can be scheduled to the customer.

At the moment, we are relying on the promised date and time but its not flexible. If we can add a work hours calendar to Accounts similar to that of Resources and restrict the booking as per this with an extendible overriding option similar to Outside Work Hours, similar to Bookable Resource, it will be helpful.