your regular maintenance will vary depending on the weather/course conditions.

Here in the Portland, OR area, the cross season tends to wet and muddy. Some courses have thick, clay-laden mud that must be washed off or it hardens and can foul cassettes, cables, brakes, etc. Other courses have gritty, sandy slop that wears brake pads down significantly.

After every race, my bike got a plain-water rinse (NEVER use high pressure water!) and scrubbing with a brush 'til it was clean. Air from a compressor blew the water out of the chain and it was re-lubed.

Then into the stand to dry until the next race. If the weather was wet, i removed the screw holding the cable guide on the bottom bracket shell. EVERY TIME a stream of water poured out of my bottom bracket shell. This last bit is key to prolonging the life of the bottom bracket itself. (And your frame, if it's steel.)

My hubs got an overhaul once during the season-- water had gotten into the front hub. The grease in the rear was actually okay, but it got repacked anyway.

Realistically-- you only need to replace what is obviously worn. I'm not a pro so I PAY for all my own stuff. That means that i don't go replacing cables and pads, etc. all willy nilly.

If your BB was all tight and gritty... then it needed replacing. Brake pads badly worn? Replace them. Brake and shift cables looking okay? Housing not kinked? Then keep 'em.

You LBS might have just gotten a little crazy with all the replacements.