So looking at a longhaul crew member with approximately 4 trips /month minus leave plus SEP/MLD. You can add on another 120 hours? Still a long way from the theoretical 2000 hours.
A long haul crew member is more likely to hit the 900 hour limit, a short haul member is more likely to hit the 190 in 28 days or the 2000 hour annual limit. Both these numbers are there as limits laid down by law. The laws are there to protect the travelling public from potentially fatal mistakes caused by fatigue. They are based on extensive scientific research.
If you believe so strongly that cabin crew are lazy and hardly do a stroke of work, please present your scientific evidence to the relevant authority so the safety margins can be eroded to please your egos. Or else can we please return to something more enlightening and relevant to BA Cabin Crew Industrial Relations.