This often causes confusion.
Flying hours are those spent on the aircraft from push back to engine shut down. Max 900 hours a year, 100 flying hours a calendar month.
Duty hours are those spent from check-in to check-out and also include standby and home standby, non flying duties and any other rostered courses. The duty limits, as posted above, are significantly higher than the flying hours.
To roster 143 flying hours in a month would be illegal. To roster 143 duty hours would be busy but not illegal. In order to achieve a maximum flying hours month including standby days of 8-12 duty hours a day 143 would not be unreasonable as a planning excercise. Very tiring though. (P.S. I have just achieved, as flight crew, close to 100 flying hours and a 135 credit hour month due disruption. It isn't that rare at the moment especially in times of disruption.)