Correcting levelling with 360° x 180° panos takes a second or two, even if you take the shots pefectly level, the stitching software might hit off slightly at first run. Levelling becomes more important with cylindrical panos as correcting would invariably involve cropping the image. Also, the point of least parallax (nodal point) only becomes important with scenes with near and far objects, like rooms etc. It is perfectly fine to take panos from a normal tripod or handheld of scenes where everything is far off like in a landscape scene. With closer objects in view, or doing the complete sphere, more work would be involved to hide the errors. Nodal Ninja do a good range of equipment for making panoramas. I have an old slightly war worn NN3 head that does me a treat.