One page for the cover/introductory letter, one page for the resume and the references.
I would say if you are making the jump from simple aircraft (bush, single engine etc, all very general terms and lose definitions, everyone is different) or starting out, one page resume is important. If you have been flying for a long time, have type ratings and are corporate, the inclusion of how you set up a flight department or were CP over 50 pilots etc, page numbers are immaterial.
Nobody needs to know how you loaded barrels or pumped your own fuel if you tell them you flew a Stoneboat in the Yukon, for example. If you are trying to get on with Jazz, having flown in busy airspace or multi-crew details might be important, but nobody needs to know if you did Dangerous goods or similar as everybody has to.
It's really situation-specific. I had my worst experiences doing resumes for ex-military drivers, guys with a 1000 hours PIC in a Herc or a (what's that 4-engine Boeing transport) who are only 25 and have little chance of being Captains in Canada again for many years. Two pages explaining the extensive and very intense training or one page saying they were 4-engine Captains? Very few employers want the details of the training, knowing in advance they are very good aircraft commanders who are likely not too interested in a Beaver in the bush.
Too much detail and the reader switches off. Too little details but very good quality, the employer will likely call to get more.
I am also become convinced that with the total embracing of technology in communications, you should not send an email saying you have attached a cover and resume. The cover should be the first thing the employer reads.
Hello please check your PM