How long can an air compressor run a drill?
I was just wondering if they make an air compressor that is efficient enough to run a pneumatic drill constantly without stopping the drill. Or is the amount of air used by the drill and bleed air more than an air compressor can output? If not, which air compressor is the best?

depends on the requirements of the drill motor and the capacity of the air compressor.
Both compressors and tools are rated in CFM at stated pressure produced or used.
if you want to run the drill constantly, get a compressor that produces enough air to do so.
For most ‘shop’ uses, you want a large enough compressor, and a large enough tank
on the compressor to store enough air so that the compressor can cycle,
running about 50% of the time when your tools are in use.