Don't think LRP is recommending 12A charging, they're saying it's safe to charge up to 12A.

Are you racing or something else? If racing there's 2 schools of thought. First is buy an iCharger duo that can do 30A or more charge with a discharger and completely cycle your batteries right before a race to heat them up and get the lowest IR. Not going to get into the debates here on the pros/cons of this practice. There are recent threads on this forum already.

Second approach if racing is that it's unlikely you'll be using more than a fraction of the battery capacity during a race. During 5 min races, even on 2wd SCT trucks, I'm not using more than 2000mah of capacity from a 5000-6000mah battery. Onroad is even less. Meaning is only takes about 15-30 min to recharge my batteries at a 1C charge. Which is plenty of time between races.

If you're doing something other than racing and you're running your packs until low voltage cutoff, then it's how much down time do you need or want. Most of my offroad brushless vehicles can't run much more than 10 minutes without the motor overheating. So while the battery still has capacity, I have to stop anyways and let the motor cool off.