Do you have tips for staying essential at work?

Since I leave work the earliest (I work 6am to 3pm) but am responsible for all intakes coming in the office, I told my boss that I would be available after I get home to do an intake from my home office if there is no one there to do it.
Since he only likes the way I do the intakes he has given me an extra 10-20 hours or so a pay period in at home every week at overtime pay, to make sure the intakes are done right.
The clients tell him this is great because I am available at hours after dinner to do intakes which frees them from using their work time to do personal things. I fax the intakes into the office along with the amount of time spent on the ohine call and write up and get paid overtime I take great notes just in case I can not do the write up immediately afterwards, and do them in the AM at work the next day.
I even was given a raise and he now allows me to work at home during bad weather to avoid the hour commute to work and the hour home which has made it easier for me. My intakes are done around my schedule between the hours of 6pm to 12 am
Their cases have increased by 23 percent since I have been doing after hour intakes and he is ecstatic.
My job is safe and he always praises my work and dedication to his office.