they even started recording the first album. There were exceptions - Supersonic being a really great one - but Noel had taken years to write a compilation of great songs, then knew he had to come up with enough new ones for a third album and would be expectef to match the best songwriting he'd done over the previous few years.
His and Liam's idols, the Stone Roses, ran into the same problem. Their first album was brilliant. It also contained songs written years earlier, songs that were favorites of their Manchester fans years before they were recorded.
It isn't unusual for a band's second album to be disappointing compared to the first, if they'd been together long enough to have a good original setlist. Noel had stockpiled enough songs for most of two albums.
I've seen fans online wondering if he might have been writing and stockpiling songs for Oasis during all the years he and Liam weren't working together. I wouldn't bet on that for most of those years, given their feuding and how much he'd talked about wanting to try something different and work with different people. But I wouldn't bet much against it, either. Knowing how creativity works, it's possible he sometimes woke with a melody and snippet of lyrics in his head, something that seemed like a new Oasis song to him. And that would have been much more likely as they rehearsed for the reunion tour, and is even more likely now, even while they're touring. No matter what he might still be telling himself and others on a conscious level about not planning to record new music.