In my experience the main cause of overheating when drilling is too slow a feed rate. When drilling with a Forstner bit I start the hole slowly to get the best entrance then feed aggressively and quickly withdraw the bit to clear the chips. Forstner bits are more susceptible to softening from heat than bits made of high speed steel.

The second cause is letting the flutes get packed with chips. The bit will also stop advancing when full so when the feed rate slows I extract and clear.

That all makes sense to me.  The one issue I have with the Blum jig is that there is no provision for the wood shavings to escape.  I have to use a screw driver to prize the shavings out and a vacuum to clean them up. 

Other than that, an excellent (but crazy-expensive) jig.  (About $350.00 now.)

This image shows the void that gets filled with shavings.