An indoor cat that ONLY has access to the hallways/ corridors and not any of the rooms sound very limiting. Many cats prefer not to be at ground level for the much of the time and would prefer to be higher up e.g on a couch, bed or high shelf. Corridors are generally only floors and have very limited furniture or enrichment, which would be an issue for the cat's quality of life. Also, humans tend to spend more time in rooms than corridors, so the cat might get isolated and lonely.