...but, there are exceptions. I usually reserve these for high speed (>45 mph) roads with zero shoulder, or blocked edges due to construction, or somesuch.

If the road is truly designated as a "share the road" with markings and signage, then drivers should expect you to take the lane fully and ride at your pace. Tough noogies if they have to drive slower behind you.

How fast should you ride? How blue is the sky? Ride your own ride.

Is this the only route to school? Can't identify a longer way through neighborhoods or otherwise parallel to the main traffic path?