What room should be larger in a studio, the control room or the recording room?

It is commonly preferred to have a larger recording room and a smaller control room, in this way it is easier to have a lower reverberation time (T60, the time by which sound drops by 60 dB since it ends within a room) in the control room rather than in the recording room.
No control room should cover the recording room acoustic print with its own, otherwise the sound engineer would never understand completely what happens in the recording room itself (i.e. instrument and microphone positioning, small details in the tracks, both in the time and frequency domain, etc.)
A practical aspect to consider is that bigger recording rooms can host more musicians for quick direct takes and become a rehearsal room in case of necessity.