No, you has not understood, all more simply than you think.
It's 'fake' reflections and is not required high quality and persisting reflections — not seen difference! (only experienced programmer can notice differences). Attentively see HL2 game or CounterStrike (or other games based on this method) — reflections on floors and walls look fine, but this too 'fake' !
p.s. You can render environment to cubemap texture each frame, but this unnecessary. Enough single pre-rendered cubemap for each sector (room)!
It's 'fake' reflections and is not required high quality and persisting reflections — not seen difference! (only experienced programmer can notice differences). Attentively see HL2 game or CounterStrike (or other games based on this method) — reflections on floors and walls look fine, but this too 'fake' !
p.s. You can render environment to cubemap texture each frame, but this unnecessary. Enough single pre-rendered cubemap for each sector (room)!