I just got a Lichfield TV to Lichfield City at Cambridge, no hassle at all. But then I've found Cambridge ticket office to be uniformly excellent for many years, so not too surprising.
I'm pretty much in the sweet spot for this 'trick', with 3 or 4 days commute a week, almost always after 0930, it will more than pay for itself on that alone. Add in not paying for a network card instead, and the benefit of cheaper tickets for Norwich and Ipswich etc. and that makes it very well worth it.
(Yes, it is a few pounds more than Hatton or Pevensey, but unlike those this is one I will probably 'genuinely' use a handful of times in the next year
)