Aerating range greens

Yesterday we aerified the range greens using 1/2" tines. These greens are not built to USGA specs. There is no internal drainage or gravel in these greens, therefor they don't drain very well at all. We maintain them at 1/2" height of cut. As you can see in this photo there is a lot of thatch in these cores. We only aerate these greens once a year. The greens on the golf course are aerated 6 times a year using both solid and coring tines. Along with our weekly topdressing and cultivating practices, there is very little thatch on these greens.