Pet hair sticks to fabric because of static and the weave of the cushion. You can't stop a pet shedding, but you can stop it building up.
Little and often
A quick pass every day or two beats a big clean once a week. Hair lifts easily when it's fresh. Once it's pressed into the fabric it takes far more work.
Use the right tool
Switch to handheld and fit the wide upholstery tool. Work from the top of the back cushions down, then the seats, then the gaps.
Don't forget the gaps
Hair collects where the cushions meet the frame. The crevice tool gets into those gaps in one go.
Give them their own spot
A washable throw on your pet's favourite seat catches most of the hair. Shake it outside and vacuum it once a week.