Always there will be difference between Site based staff and HO Based staff. HO Based staff will be only involving in administration, Finance , HR, IR, Operations control, Contracts and Tender Quotes, etc., whereas the Site Based Staff are actively involved in Maintenance and Execution of Jobs which required 24 hours and 365 days availability for these activities. That's the reason, the site based staff are normally getting extra previleges like Transport Facilities, Free Lunch, Dinner (if continuing in Late night), evening snacks and Tea/Coffee, Extra Site Allowance, Free Accommodation in addition to HRA (what company pays for all the HO & Site Employees).
Even if you declare Saturday working hours is upto 13:00 hrs for HO Based staff also will not hamper any job at Site. But if you declare holiday on Sunday also will have great impact on Monday and in the progress and quality of work.