That's a great approach. Periodizing your training can help you avoid plateaus and prevent overtraining. I've also found that focusing on endurance first and then switching to pace work helps me build a strong foundation for speed. It's all about balance and patience. You can definitely improve both pace and distance simultaneously, but it's crucial to listen to your body and not try to do too much too soon.
Good point about conserving energy! I've found that starting slow also helps me focus on my form and get into a rhythm. Then I can try to pick it up later in the run.
Try shortening your stride and focusing on quick turnover. It's all about cadence, my friend! You got this.