I am just getting the hang of LR, Regular and HV attys my own self but I will share what little I have learned.
LR's use up a battery FAST but basically make 3.7volt vaping SEEM like 5 or 6 volts. If you HAVE 5volt or more, probably no need for it.
Regular attys seem to range from about 2.2 to 3.5 ohm or so They work at 3.7 volts but not as much vapor as an LR at that voltage. They also work at 6 volts, but they may be a fairly hot vape depending on just how much resistance they have.
HV attys NEED 6 volts (Maybe 5?) or more for a decent vape.
I have devices that can do 3.7, 6 and 7.4 and I am just really starting to figure what setup works best for me.
At 6 volts I use both regular and HV attys- the regulars put out more vapor but its very warm. When I use an HV atty I get almost as much vapor but its not quite as hot- usually better for me.
Hope that helps.