Jobs can be anything from small business, web design, CPA practice, law practice, moonlighting Dr., Nurse, etc.

How long to hold that seniority? Depends on equipment, domicile, attrition, and growth. I can tell you that with 50% seniority in domicile, you could easyily bid for any specific non-holiday weekday or weekend that you needed.

Depending on equipment, that could reasonably take anywhere from 1-5 years, or even more for small, super-senior west-coast bases.