Stopwatch vs stoppage time – why do rugby and football use different timekeeping systems?

The clock at a rugby union match may significantly underplay the actual duration of the action.

In the autumn, when South Africa wing Cheslin Kolbe booted the ball into the stands to close out victory over Ireland, the Aviva Stadium clock, and the little graphic in the top corner of your television screen, read 82 minutes and 22 seconds.

In reality, with a raft of television match official interventions, cards, replacements and injuries, the action had stretched north of two hours.

However, the match timing is halted for each significant stoppage to allow the right decisions and treatment to be given.

It keeps ticking as players set up for scrums, line-outs or line up kicks at goal, although referees have ‘shot-clock’ time limits that they apply to each of those aspects of the game.

The advantage for the crowd is a clear sense of how much time a chasing team has to overhaul their opponents.

Rugby’s rules mean that full-time is only blown when the final passage of play comes to an end, not automatically as the clock ticks over to 80 minutes.

The clock ‘going into the red’ to show that the next stoppage is the end of the game lends added drama to the finale of a closely fought match.

However, rugby’s authorities also know that the fact that any given fixture can spill over to north of two hours is far from ideal for broadcasters, fans or players.

An emphasis on speeding up stoppages and limited down time was a key part of World Rugby’s Shape of the Game conference in London earlier this year.

This article is the latest from BBC Sport’s Ask Me Anything team.