Peak vs Off-Peak is this enforced for the sake of a few minutes?

[Kmo86]

Are conductors bothered if people have wrong ticket off peak in peak times? I regularly get trains around 9am so the price can be over £1 more (I have disabled rail card) for case of few mins. Train used to be 9.04 meaning I’d get the off peak cheaper rate. Now it is 8.55 if I buy ticket before getting train I get charged the higher rate which is correct tho annoying for sake of 5 mins. If I get on train and buy ticket on train which I can as there is no barriers at the station the conductor has twice charged the cheaper rate. First one who I have spoken to a few times just charged cheaper rate saying it’s only few min before 9 so not worth charging the higher price and today they was going to charge higher price but I only had the money for cheaper price so he accepted that. Also I have been on train in afternoon with off peak ticket and never once been told I should have the dearer ticket. I’m not even sure when peak time is in afternoon but have been on train with off peak ticket at most times in afternoon at some point so must have been on with off peak ticket in peak times.