Snaking the shower drain may be needed every year.
The Bio-Clean people suggest their product to help the drains stay clear., Terry

Does BIO-CLEAN digest hair?
Yes. However, it does take much longer than most any other organic material. In drains, soap scum, skin oils, etc. bond hair to pipe surfaces. BIO-CLEAN digests these other materials more quickly, which releases the hair to wash downstream.
Bio Clean

• Bio-Clean (click here)