It is also recommended to worm your dogs every 3 months for roundworms as Toxocara eggs ingested by children can cause blindness. Having met one young adult going through losing her sight because of careless dog owners I could never forgive myself if I didn't keep on top of my own dogs' worming.
Tapeworm threatens livestock health so ensuring a good tapeworm treatment every 3 months is important if you are on farm land at all with your dogs.
Lungworm depends on your area, Bayer do a very accurate map of incidence across the country. In a high risk area, the preventative lungworm treatments must be given monthly. Since it can cause bleeding disorders that can be fatal, if you are in a lungworm area it would be foolhardy not to treat preventatively.
In any case, your vet will be able to help you work out a worming regime with effective products, so please discuss any worming queries with them!