Grooming cats question - trimming claws

[BaitandSwitch]

I am reading a book regarding bringing up kittens, and it states in the chapter on grooming that the nails need trimming weekly. I had hoped that the scratch poles would have taken care of the growing claws though? Any advice, thank you.

My 4 cats go in and out through cat flap. I've never cut their claws. They need them for climbing trees in garden. They also have scratching pads in house. They never scratch me.