It's ALWAYS the state who determines it. Every state has its own nuances. Overlapping work time periods generally won't count separately though.
Think of it like this: If I am working for a company 80 hrs/wk for 6 weeks, and someone else is working 40 hrs/wk for 1 company and 40hrs/wk on the side for another for 6 weeks, it's still 6 weeks of engineering work. I don't get to double my 6 weeks to 12 to average 40hrs/wk. Likewise, the other person doesn't get to count their 6 weeks as 12 even though they were working effectively 12 weeks worth of work.
Many states, if not all, will grant 1 yr of credit towards a PE for a MS. Similarly, PhDs actively working in their engineering field are generally granted PE licenses without even testing. So, you could be a professor at a University, and simply apply for a license in many states and they will simply issue it.
Also, work that counts towards a PE license only counts AFTER you graduate with your BS. I worked as an engineer, starting in 2002. There were years in my career when I had already earned my Bachelor's in Business, but was a Senior in Engineering, but I was teaching Engineering 250 courses at Wichita State, because they were CATIA/ENOVIA/DELMIA courses. They were more technical courses, than theoretical.
And even though I was faculty at WSU, and I taught hundreds of degreed engineers over the years, I was unable to count any of that experience towards my PE.
Working as an engineer during a MS program DOES count toward a PE, so long as the work is actually engineering. Most, if not all, states have an exemption request for work not done under the supervision of a PE, so long as it can be verified that it is actually engineering work.
So, don't worry about it. The point is not to see who can get their license the fastest. Be patient. There is always more to learn and become proficient at. So, put in the work. Put in the learning. You'll get there.