A red bulb is fine for viewing purposes and to raise the ambient temp on the terrariums, but they can throw off a lot of heat so we only use 1, 15watt ZooMed red bulb in our terrarium fixtures. If you are using more than one 15 watt bulb make sure you are monitoring your temps carefully. (Of course I assume you have a UTH for the warm hide as well.)
It should be fine to leave a red bulb on 24/7 especially in the winter to keep your enclosure warm in cold drafty conditions like most of us have in our homes at this time.
Those ZooMed 15 watt red bulbs are tough to find, so you may need to do some checking on line to get them.