Shynobi, it depends on the particular device what resistance you build your coils for a regulated mod. For your case, the ipv3's chip allows for voltage between 1 and 7volts. This means in order to maximize the ipv3 capabilities of 150w and get full range of power, you would need to build a .33ohm coil or lower.
Advice regarding building higher ohm coils goes toward other high wattage regulated devices that do not have a buck down chip capable of giving a full range to low ohm, high wattage vaping. They begin their range at 4volts without a buck down chip - you would easily hit the max power of the mod with low ohm builds, but would not be able to Vape the lower wattages as the voltage minimum would not allow for it without a buck down to go below 4V.
The ipv3 is designed for lower ohm builds in this regard.
Hope that makes sense.
- Bboy