You only need as many fans as there are connectors on the motherboard. Adding extra fans will draw more power from the PSU and you might risk overdrawing on a cable line with added adapters causing a shortfall on the 12v rail, or a fan not operating at all, the one that you'd really want to work more than the others, most likely. If you have any fans using the same cable line as your hdd, the hdd will suffer with lagging and freezing while it waits for its turn of the power source.
Your Rig would have to be a rather humungous system to need so many fans, something like 3 video cards, 64gb of ram, 4 hdd's, etc.. and then you'd need a 1200 watt PSU to supply power for all of that.
Just stick with the standard setup and you won't go wrong. Make sure the case is big enough to allow airflow and ventilation, don't have it in a tight corner or under a table surrounded by furniture or stuff, and keep away from areas that might attract dust.
You don't need 3 intake fans, one is more than enough, If the Pc case is on the floor and the intake fan is close to the bottom of the case then you will be subjected to a lot of dust intake and pet hair if you have any pets.