Past Perfect Continuous/Past Perfect or?

This resource states, "The past perfect continuous tense is like the past perfect tense, but it expresses longer actions in the past before another action in the past" (emphasis mine.) Therefore, if you do not mention "another action in the past," you should not use the past perfect continuous.

The same resource states: "The past perfect tense expresses action in the past before another action in the past." Therefore, you should not use the past perfect if you do not mention the other action in the past.

Without knowing the context, I would recommend the simple past as follows: "I worked for the company for 10 years."