retinal detachment is a very serious problem  it's  treatment  ,though  possible  but results  are uncertain eve in best hands. you will  agree with the proverb  'precaution is better than cure '.and for a sight threatening  problem  it's more judicious. the decision  of performing  it in one sitting  or multiple  sittings  depends  upon  the are involved  and that decision  has to be taken by the person  (doctor)who is performing  it .I think  I m clear