Software testing specialists use all accessible resources to apply the best performances to employ for their work on the project.
It is a common known fact that what is an excellent practice for one software tester or one software testing company is not absolutely the best practice in another organization. Best is significant only in the circumstance of the software testing project.
Nevertheless, there are many skills that move from one project to another. So you shouldn’t forget your skills in any other projects or in other fields.
There is a great package of information that should bring with you, even from apparently unrelated areas.
Certifications don't teach anything; it is just a tool to measure someone’s knowledge. It is just one element that might help set purposes for you to work towards, or provide a structure for your own training.
Software testing company, or any professional company, will not teach you anything. But you will have an access to resources and have a direct contact with great number of software testing professionals who are interested in conducting the best work.
You should do your best to become a member of these teams. Joining a company and actually making use of it or contributing to it is where the value is.
Summing up, specialists are always trying to get more knowledge and information, to put that information and skills to good use improving themselves, their testing project, and their software testing team.