I've done couple of Odoo projects for my clients and I'm still not quite sure what's the reason that company would want work centers in Odoo to be set as workers and why they wouldn't want that?

The reason I have configurated all my Odoo projects so that work center = worker is because of workload management, but I'm not sure if this is the correct way to do it. 

Most of my clients are mechanical engineering shops and they usually have operations like 1. Planning, 2. Sawing, 3. Welding, 4. Machining and 5. Assembly. They also usually have 5-10 workers in total who all do these operations. Some workers can do just 1 operation and some can do multiple operations (not at the same time obviously).  

The reason I have workers configurated as work centers is because if I would have operations set as work centers, in my opinion, I wouldn't be correctly able to display the actual workload (green bar) in GANTT chart view. That's because maximum working hours for 1 work center is obviously 168h/week (24/7). And let's just say that I would have 5 people available to do Welding this week. If all the workers work standard 40h/week that would mean, I would have 200 hours available (5x40h). This way, if Welding is set to be its own work center, the workload wouldn't be correct, since the maximum working hours for 1 work center is 168/week (24/7).

Back to my original question, is it normal to have work centers set as workers with manufacturing industry clients that have processes/operations like mentioned above? Moreover, what would be the case where operations would be set as work centers, because I can't seem to see how can that even be possible in workload management perspective? 

Thank you in advance!