Painting from outdoor and in studio re great different. Each has its own advantage.
One is tempted, even in good weather, to spend all one's time working indoor, where there is a vastly greater availability of art materials than outside. There are also larger surfaces on which to work, sturdier easels, and chairs to sit on for reflection. All this without even considering the pleasant distractions of an occasional phone call, or a snack to calm the nerves. Nor does the light change as much, or the wind knock the painting off the easel, or the bugs bits. Add to this that the outside is generally unfriendly to bright color. Thus a work painted indoors is very likely to have much greater coloristic invention than painted from nature.
Working from nature is much more fun and spontaneousness. By working outside I collected my repertoire of color, achieved my focus, and assembled my characteristic subject matter.