In lap, change tyres, out lap, hot lap.
At Australia thats about 5 minutes. At Spa it will be well over 6.
That's only a problem if you are at the cutoff every single time. Like I said in my previous posts we could simply allow people to finish their hotlaps which saves a massive amount of time. In Q1 we saw people were getting out and starting a lap in time with a minute to spare. Over time they'll get more efficient.