Sir,
It is simply a matter of what you have learned and what you are used to. With ~1700 hours of experience on your bird, for better or for worse you have adapted the eye/hand/motor memory coordination to whatever eye position results from using "three clicks' of seat elevation. As I see it, you have two choices: 1) Continue to fly with what you are familiar with st 3 clicks or 2) Adapt to your captains' polite suggestions that you use 5-clicks - and suffer through the motor muscle and hand-eye realearning process.
There is only ONE pilot that direct you toward the correct course - and of course that ONE is YOU!
We do not know who you fly for or in what environment. With 1700 hours on type, you may be close to an upgrade and be in need of some "Captain's Recommendations," or not. Again, only YOU know what is the correct seat position for you. And yes again, it really IS a matter of what you have learned and/or your motor coordination functions have adapted to. I better answer I simply cannot offer. Other questions that you must ask and answer on your own include how serious were the 'suggestions,' and how much weight to captain's comments carry at your company, concerning upgrades? Whether it it so be 3-clicks or five, the choice ought to be about safety - and I suspect that you already know that. Good luck!
