Apologies in advance for waffling on...
I've been buying advance tickets for my 3 day a week commute between Earley (just outside Reading) and Bath for over 9 years. The cheapest way to do it is to split the journey, with walk-ons between Earley and Didcot, and advances between Didcot and Bath.
Initially I caught the 0726 from Reading. Then that (ie. the advance bit between Didcot-Bath) went up, so I caught the 0656 (very quiet!). That went up, and I switched to the 0742, having to change at Swindon.
Eventually the 0742 went up, and the only option was the 0858, getting into Bath at about 10am. Luckily work is pretty flexible so it wasn't a big problem. But it meant I went from low occupancy trains, getting into the office nice and early, to pretty full carriages and practically late for work.
Strangely, for September the best (and only) option was advance 1st class, with a change at Swindon. So at the moment I'm getting 2 cups of coffee and pieces of cake for breakfast, as well as posh seats! (Although I don't think they're actually any more comfortable, and it's a bit of a stretch to reach my laptop on the table.)
But for the last lot of tickets I bought, before the ^10 singles became available unfortunately, things took a big turn for the worse. There were no cheap advance tickets at all before 9am, and the best option became straight returns between Earley and Bath, again not getting into Bath until 10am. This meant my travel bill for October jumped by over 33%, from approx ^300 to over ^400.
It might be that the lack of the usual advances is due to the ^10 single promotion, and they might come back when that finishes. But based on the trend over the last 9 years, I suspect not