Much of the activity in Ireland outside of Dublin Terminal Area and Shannon Highlevel with the Atlantic Rush focused on the Irish Landfall points would come under that heading.
But even under UK rules, if they work a 4 hour shift in quiet airspace, then they still need a pro rata break (which would be 1 hour). So you don't get more hours covered by the same amount of staff. You get the same amount of coverage as though you had staff working 2 hours on, half an hour off.
If you are short of staff (as Ireland appears to be) and don't have the cover, you're still up sh*t creek. You still hit the wall, just 2 hours later than where controllers need a break after 2 hours.