Starters are one of those devices that will fail depending on how many hours of use they have and how hot they have become during that use.

If you utilize the starter to start the engine within three seconds, and the engine is maintained in this condition, the starter is going to last a very long time. But, if the engine typically requires 15 seconds of cranking to start, the starter temperatures climb dramatically and the life of the starter is summarily reduced.

I remember, distinctly, a 350 chevy V-8 that I changed the starter on. Bought the typical rebuilds that are available for less than $20. (at that time).
Rebuild would last about 18 months. That's it. This process would repeat itself. Apparently I never learned that a typical rebuild is a POS.

It's all in the duty cycle of the starter, and, in the case of it's replacement, the quality of the rebuild.