TL/DR Heel drops aren't a cure-all, be aware of your own unique situation. Stretching, warm-up, and adding training stress more slowly may help.
I had achilles tendonitis on and off for 2 years. I've been training for the last 8 months without issues. To add a slightly different perspective than everyone else. I don't think heel drops will work for everyone. I tried the heel drops and they may have helped a little, but they certainly didn't fix the problem, and the tendonitis would come back. What seemed to work for me was adding lengthening, warming up properly, and adding stress in my training more slowly, after trying the heel drops for months.
Before I run I roll out my calves, and do some warm-up exercises like glute bridges, runners touch, etc. After I run I would stretch my calves, both straight leg and bent knee. I would hold each stretch for 2-3 minutes. Additionally, I made sure to progress my training very slowly. I only ever increased the training level when I knew I was ready. Usually 4-8 weeks at a given training level without issue before progressing.
Some other small things I've tried is I wear zero-drop shoes as my everyday (non-running) shoes to help lengthen or prevent shortening my calf/achilles. I wear socks around the house to keep my calf/achilles warm. And if I get the slightest flare up of calf soreness I use compression on my calves. I also avoid low drop shoes and definitely avoid spikes for running.