Just want add little more:
One Shift:8 hrs,
Small centers: One Shift-8 to 2pm or 8am to 11am than 13pm to 16pm or 12pm to 15pm and Single window only.
Big centers:8am to 2pm, 2pm to 8pm and
At...
more... some A1 grade centers extended hours:5.30am to 8am(limited period shift-PNBE-trial basis) and 8pm to 10pm -One or Two windows Only.
Some PRS Observers 2nd shift holiday on selected occasions some works without any such breaks.
#many PRS have 15min Tea break at 11am(DBG), Or 15min Duty change break / Lunch Break.