Rather than provide sufficient capacity, it is often suggested that the answer is to encourage flexible working hours so as to spread the load.
That might make sense on the London commuter network. But away from the capital things are different. Firstly providing the extra capacity ought not to be prohibitively expensive because we are talking about things like allocating a single extra unit to the Melksham line or running the Cardiff-Portsmouth service as 4 cars instead of 3. Small relatively low cost changes which would make a real difference. We are not talking about spending 15 billion on tunnelling under the centre of a city which is what providing extra capacity in the capital means. Secondly, the regional railway is certainly not deserted outside of the peaks. They are busy at commuter times but their passengers are not overwhelmingly commuters. Off peak trains may not be full and standing but they are usually pretty well used with business, education and leisure trips, foreign tourists etc, so those extra coaches are not often carting around fresh air.