Are there (sizeable) distros that does not allow you to install multiple DE's and change between them?

Bottom, it was the primary reason I switched to FF instead of chrome on my phone

The factory must grow!

Because using a yearly average is useful to account for fluctuations in power generation due to the change of the seasons. It might produce 50% of its power in 3 months if the fall usually is particularly windy in that part of the world.