I think building xc depends where you instruct. I'm a firm believer in flying to other airports to do approaches rather than constantly doing approach after approach at your home airport where eventually the student memorizes all the altitudes and fixes. I like to mix it up so the student isn't always familiar and has to be paying attention to what he's doing during each approach. I instruct at EVV (Evansville, IN) and there are 3 other airports within 20 miles and a 4th within 30. If a student is working on his instrument rating he knows enough to realize that if I'm taking him 50 or more miles away to do approaches that I'm wasting his time and hard earned money. The only time I can do that is if its one of the required xc's for the rating or he still needs to build some xc time to meet the 50 hours required for an instrument rating. Now if you instruct in a not so densely populated area I could see where you might log more xc time because there aren't nearby airports. With that said though unless you instruct at an actual flight school I think most mom and pop flight instructors like myself are having a hard time building time because the cost of flight training is through the roof nowadays. I rarely have ANY instrument students and about 80% of my private students get no more than 20 hours and I never hear from them again. When I first started instructing 2 years ago I started doubting myself as an instructor thinking maybe it's my teaching skills scaring students away but after talking to other instructors at the nearby airports they're seeing the same results. Flight training is just too expensive now for students to stick with it long enough and help you log some xc time. Im at 720tt with only 180xc. Luckily, my FBO has a charter department and I'm currently at Flight Safety getting a SIC rating in a beechjet. So when I do hit the 1500 hour mark ill have my 500xc. But I think any instructor out there who isn't in a situation to get some xc time somewhere else is going to have a hard time getting that 500xc