The service manual gives you one way to perform a task but it often isn't the only way and sometimes isn't the best way. I remember when I worked in a GM dealership (we were on 'flat rate' for most warranty work) one of the tradesmen took it upon himself to show a district service manager for GM "another way" to perform a warranty task which cut the time required to perform the job by half. He thought he was so smart until the DSM had the flat rate labour GM paid out, changed for that particular job (we used to get credited 1 hour for a job that took half that). That particular mechanic wasn't very popular for some time....