I used to have an 04 golf TDI, and it would idle for tens of hours throughout an OCI, i would routinely have it idling for up to 2 hours, at least a few times a week. Analysis results were always flawless (of course, the mobil 1 TDT helped im sure)
PS, the reason for this is, I sometimes had to take naps in my car, and if it was hot or cold out, I would have the A/C or heat going.