Ventilation is a subject and function that many many builders, building control and home owners just ignore. Ive lived in properties that had poor ventilation and as you describe condensation can be a major issue.
In recent years, I took the subject far more seriously, on my last house build, I myself fitted a whole house ventilation system whilst the building was a shell. Every wet room had extraction, every living room was fed filtered, warmed(use of heat from exhaust air), dehumified air. The system worked extremely well, temperatures were constant in all parts of the rooms and humidity controlled. When an occupant had a shower the system would detect higher humidity and ramp up the flow rates to remove this moisture, falling to idle once humidity had returned to normal.
On our old property we live in now, I have installed several constant humidity controlled extractor fans in the wet rooms and ensured inlet air is available from vents. Moisture is controlled via aircon system.
