Must say solid wall against solid wall in a non wet area I have, on a couple of occasions, just used my flexible grout of choice (Once in my own bathroom and once in my ex's) years later they are absolutely fine.
Workwise running up to xmas is totally mad for me atm. Turning work away every other day (sickens me 'cos I know Jan/feb will be slow but peeps want it all doing now) Never earned so much this last couple of months! Even took a labourer on for current and next job as I'm grabbing like a good'un and under tight deadlines. Had a £150 tip on my last job - he even did an oil and filter change on my van gratis while I was fitting his bathroom. Don't want to come across like I'm bragging (I'm usually on here moaning about not enough work) just want to spread the good vibes about tiling I'm feeling presently.