Bryngwyn, an 11-16 school on the edge of Llanelli, was inspected in March.
For headteacher Dr Margaret Williams the use of self-evaluation, a nominee and a peer assessor all made a valuable contribution.
"They didn't make it easier," said Dr Williams, "but I think they added to the quality of the inspection process. We felt more involved.
"We had more of a sense of ownership rather than it being something done to us, with a report presented at the end."
The school embraced the process of self-evaluation and involved all interested parties. This meant it was time-consuming but it is expected to have long-term benefits.
"Once you've done it you can update it each year, so when the next inspection comes we'll be up to date." The use of a nominee meant the process was better informed, said Dr Williams, who appointed her science line manager to the role.
With the inspectors working to a tight time schedule, the nominee could answer questions and present evidence.
"Someone was on the team to point people in the right direction and ensure there was a smooth flow of communication," said Dr Williams, who believes the role also helps professional development.
An above-average proportion of Bryngwyn's pupils are entitled to free school meals or have special educational needs.
The inspection's peer assessor came from a similar school, which meant the team had "up-to-date experience in a similar context".