Time and again I will post and say basically that when you do the timing belt you should also do the idler and tensioner pulleys as well as for the water pump.
I would say that probably 97% of the time I am presented with people who say that this is overkill and/or just too expensive to do. What's the cost of cooking the engine? Many however will drop big $$$$ into "enhancement parts" but scoff at performing the basic maintenance needs. Go figure?!
I've worked in the automotive industry and have actual related experience. Have you ever had a customer come back after you told them, both verbally and in writing, that you need to replace just more than the timing belt itself? They don't get it. Even when presented with facts they can't understand that they should have spent, for example, $500 on a complete timing belt & accessory service, not the $100 on just replacing the belt as requested, to end up spending $1,000 (or more) on a 'new' engine. (NOTE: I used these dollar amounts for demonstration purposes only.)