Is more than just the factor of rentability to consider. If you rent your house to too many parties or allow your tenant to sub let the rooms of your house, you may find yourself in big trouble later. Not only you may find it hard to manage in rental collection but the condition of your house may be in a undesirable state when your tenants shift out later. Not sure in Singapore, but in Malaysia, normally we do not allow tenant to sub let the rooms to other people.
Of course, given a choice, who would want to rent out to so many people? Would you want to rent it out to a group of 'friends' or leave it empty for 6 months? One has to face the reality in a slowing market, and it is v common for HDB flats to be rented to a group of friends/students/bus-drivers etc. And rental collection is usually to a single person, instead of collecting from separate groups. My friend just rented out his 5 room Punggol HDB to a group of PRC students. Do they secretly sublet? My friend wouldn't want to know or guess.
Just to add that with technology advancement such as Internet transfer, rental collection is a breeze now compared to the older days. I haven't even stepped into my unit for more than 1.5 years now. There's no need to micro-manage. An investment property becomes just that. An investment. And if we treat it that way in this forum, we would probably have less disputes and more useful information.