theres no actual rule, basically every weld is different and the metal and shape and size will vary how much heat is needed and how much is lost. the puddle will be a shiny bead that looks like mercury or molten solder, dancing as the wire burns and feeds it.
you need to keep it really steady to get a nice line, otherwise your welds will be line my earlier ones, a bunch of dots everywhere. yes if done well enough they will hold, but its inefficient in wire costs, and really slow if your welds are dirty. it's best to just get the pretty and steady line.