Will cooking meat with the thermometer in affect the cooking time?
There are "potato nails" marketed for speeding up cooking of baked potatoes by conducting heat into the center of the potato. This testing showed about a 10% reduction in cooking time. Cooks's Illustrated also tested potato nails, and showed a 7-minute reduction over a 75-minute control. They also tested a potato with five potato nails, which reduced cooking time by 11 minutes.

Obviously potatoes aren't meat, but it doesn't seem unreasonable to extrapolate.