I drilled 64 holes in varied concrete. Most in precast single rod 3/8" reinforced steps at a school. Holes size was 4"w x 6"d . My average drill time was 35min per hole. The best speed I got was when I used a thick thick slurry. I used two bits for the job. A consistent strong anchor for the drill base is the key to speed. I used a Milwaukee vacuum pad and 1/2" expansion anchors depending on location. This was my fist core drill job so there has been a learning curve but for $80 I don't think it get much better in the durability of the bits, both still have over half life. On the next job Im I'm confident in biding the time required at 45min per hole. There was no hired help operating the core drill it was all me. Thanks EDiamond!