The quality of your work depends partly on how long one thought gets to remain uninterrupted.

Ideas develop when they are held continuously, and interruption resets the process. A thought that gets ten uninterrupted minutes goes somewhere a thought that gets ten interrupted minutes never reaches, because the later stages depend on the earlier ones still being loaded. Duration is a component of quality.

Measure how long your longest uninterrupted stretch of thinking was today. If it is under half an hour, that is probably the ceiling on your work. Extending it is often more valuable than adding hours.