The test preparation company (I managed 23 years ago) hired an accounting firm. I discovered the CPA accountant (and his staff) were cramming hundreds and hundreds of tax returns through each tax season.
Obviously, the business and individual taxpayer returns were not getting the attention they needed. (Later I found out the vast majority of tax preparers and accounting firms operate the same way!)
Some CPA firms and accountants send their tax returns and bookkeeping to an outsourcing firm in India.
I was paying a very high price for this.