I see here that there are others who don't seem to have the same bodily functions I have. I was amazed when I first came across this.
It seems to me that in a 'normal' person the intestines must pulse every now and again and when the remains of one's digested food reach the end of the "pipe" it isn't a choice, one has to 'go', there and then, or risk causing an injury trying to force it back.
And yet others seem to experience a different situation where the feeling of needing to go lingers on for hours, and they get this peculiar idea that everyone can simply choose when to go and so it can wait (or peculate ?) until they go home !
It is a strange world we live in.