Are you taking about soaker hoses? We gave up on those years ago. They always ended up clogging.
For about 5 years now we've been using inline dripper line from Dripworks. The most common one we use has drippers every six inches although we do use some with drippers every 12 inches. We haven't had to replace any of this drip line yet.
We have a large drip system that's been in place for 25 years. There's always some kind of repair needed, although it's usually damage from some water left in the main lines during the winter.
