Dave, I disagree. There are opinions given by all sorts of people as to what is 'reasonable'. None of that forms part of the law, nor does it constitute official guidance (I will allow an exception for Scotland, where I believe official guidance has been given). In fact, the word 'reasonable' does not appear anywhere in the Government instruction (which is law, not guidance). It does, however, specify 'once a day'.
At the end of the day, it's down to your own judgement and conscience what is acceptable and appropriate. It's not for me or you to attempt to influence anyone towards any particular answer, though it may be ok to suggest factors they might like to bring into consideration while they're making that personal judgement. Nor is it ok to say 'this is what I'm doing; you should not be doing more'. I have my own opinions of what is appropriate, and I will apply that to my own riding. It may be more or less than your judgement, but that's ok. If the law changes, I'll adapt to whatever the new instructions are. If that's a total ban, so be it.