Yes. Most of those heaters are 1200 to 1500 watt consumption with both elements on. 1500 watts on a 120 v. circuit is 12.5 amps. Considerably more when they cycle on. Most house circuits are 15 amp or 20 amp. I always use 1 per circuit, and that on 20A circuits I know have no other heavy draws on them.
Also, it’s a good idea to upgrade the outlets to commercial grade 20A outlets. The 15A residential grade outlets are prone to failure after a while, under heavy loads. Ditto for the plugs on the heaters. It’s always a good idea to run one on “high” and, 10 / 15 minutes later make sure the plug (or your outlet) is not getting hot! Check ‘em again every month or so. I’ve taken plugs apart and the damn Chinese just laid the wire against the back end of the plug blade... If one has the slightest doubt, go to a big box building supply store and buy a heavy duty plug as a replacement. (If not familiar with such work, find someone who is.)
Good advice. Yes, I wired my shed, 12v/24v solar system, box van, garage. Currently planning breakout panel replacement w/transfer switch for 10kw dual fuel generator and solar system.