On my ride through Africa had heavy duty tubes, only 3 punctures but the fastest one to go down was 20 minutes. Know this as blew it up and rode on for that long before having it affect handling ( wanted to ride out of soft sand to a somewhere a bit firmer so inflated it 3 times). Other puncture was slow, blew it up in morning and down to half pressure 4 hours later. 3rd one was losing pressure over night about 1 bar so very slow.
Well worth the investment for the much more expensive tubes, seem to seal hole and not rip.