>>5922630To some great degree, yes. Then, as always, it depends how you practice.
If you read a book absent-minded, you won't gain much; if you sketch outside without clear study goals, you won't gain much. Imagine you want to learn about architecture simply by looking existing building, ask yourself questions, be curious: how tall is this? how many floor? how tall are each floor? how is it oriented? wait a minute, are the walls receding or is it perspective? what kind of decoration? how are they related with each others? what kind of columns? what symbols did they use?
Etc. etc.
Now, that doesn't mean you can't and shouldn't work from books either. There are plenty of good books on a wide variety of topics related to architecture or landscaping.
The problem lies with your question: it's under-specified. "Landscaping" could refer to making easy-going landscape painting, for which you barely need more than a good composition with a few harmonious big shapes, and a touch of perspective. But as you're also mentioning architecture, it could also mean that you want to go far deeper, study what kind of trees grows where, how do they change over year, etc.
Sketching outdoor is basically an open-answer: just study what you want to study.
