I carry two spare inner tubes along with a repair kit, but circumstance's dictate whether I repair the puncture or use a new innertube. For example if bad weather is threating later in the ride, I will repair the inner tube there and then while the conditions are good as I do not want to tempt fortune with a good inner tube, get another two punctures and then find I may have to repair one possibly later in wet and muddy conditions. If time is a priority then its always a new innertube.