I am 70. I had colonoscopies at 50 and 60 with no findings of concern except some minor "articulitous"(spelling?). At what age is it recommended to stop taking colonoscopies?

I a procedure due tomorrow scheduled by the V.A. and just became aware so I can't ask them these qkuestions. I have a prep kit issued from seemingly two sources and am concerned there may be redundancy. One sent pills (2 - Biscodyl 5mg tablets) and 3 bottles of Mag. Citrate. Are they redundant or are they eant to work in concert with each other?

Also, from my last colonoscopy I vaguely recall an antibiotic was prescribes but may be mistaken. None has been sent to me to take in advance of the procedure this time. Are anti-biotics needed as part of the prep?