Everything depends on your soil conditions. Chickens constantly peck the soil and in doing so, they pick up worm eggs and swallow them. Then it starts the worms lifecycle.
Warm, moist/wet soil is worm soup. Cold, dry, or desert like soil (sand), not so much.
This is why I have sand in my pens, coops and nest boxes. It's easier to scoop and dispose of it.
Our soil here in north Florida is normally warm and moist and I usually worm my birds monthly. However, I've skipped a couple of months due to our record consecutive days of below freezing temps, and we're in a severe drought.
I'll worm my birds in early March and continue worming monthly. Spring time is worm time, like everything else coming back alive and reproducing out of cold winter.
When it comes to tapeworms, chickens must eat an infected insect.
Insects are the host for tapeworm infections. Not all insects will be tapeworm infected. It's called the 'Indirect lifecycle' of worms. Whereas with roundworms, it's called the "Direct lifecycle" of worms.