I use two different energy sources with two circuits.
One source is running my cheap construction market lamps and the other one is for the grandes and mathmos lamps ;)
I can switch them all one with two circuits.
Its also good because in the summer its not possible to run ~20 lavalamps at the same time in one room.
At this time my mathmos lamps are all in a good conditions.
I think that they life much longer than the cheap lamps...
Its more important that you protect them against UV strahelng.
Dont put them in direct sunlight...
If you have much lamps you may have to think about a window film which is absorbing UV strahelng ;)
Is also nice in the summer :)