The artist earned a crust in his early years by working for a number of well known publications. It provided him with financial support as he worked out how he might go about establishing himself as an independant artist with the freedom to work in whatever ways he wished. He did, however, find this type of work to be entirely uninspiring and soon sought an escape. Perhaps the benefits of his time served in these companies was not immediately obvious as he started to move into painting and engraving, but with the luxury of being able to take stock of his entire career, we can see his drawing skills popping up all over his career. They would provide the lines of form for his watercolours, the initial preparation for his detailed oil paintings, and also provide the guide for his engraving tools on wooden blocks.
Homer's early watercolours were essentially washed drawings, where clear lines of pencil would produce form, before generic areas of colour were added with subtle watercolour. The same technique was used directly onto wood in order to lead his eye when producing engravings. The artist also produced huge numbers of figurative pieces and these would require large amounts of practice, with the fastest method being through simple sketchbooks. To adjust paintings on the fly is very difficult, particularly for watercolours, and so it would make much more sense for figurative artists to practice their skills through sketches as well as planning future compositions using this simpler medium.
Winslow Homer is most famous for his classic oil paintings, such as Breezing Up (A Fair Wind), The Herring Net and The Fog Warning but, in truth, his ability was much more diverse than just that medium. He travelled frequently, once he was financially able to, and worked prolifically whilst away. The artist adapted to his situation and worked exclusively in the medium of drawing and watercolour, because these were highly portable methods. He visited many picturesque parts of the country, as well as journeying abroad, and carried his instruments of art with him. Many notebooks have been uncovered from his career which provide whole series of artworks, some fully completed watercolours, whilst others were rough sketches aimed at exploring elements of a later composition around which Homer felt some uncertainty. Portraiture is famously difficult to master and so many of his sketches would focus on capturing the human body correctly.
The medium of drawing has received a greater focus in recent generations, with exhibitions popping up all over the world where an artist's work in this medium is centered on entirely. Academics have started to respect these contributions much more readily and the public have also started to show more interest in them. Of the drawings remaining from Homer's career, many are figurative portraits of soldiers during his period working in the American Civil War. It would have been easier to carry a simple pencil and pad around with him during this conflict. He would have taken a spare moment to work, when other times he would be occupied with his own safety. You will notice that this series of drawings use a consistent set of tools and materials, underlining how he would be restricted in how he could work during this period. In some cases he would then take these studies into his studio and complete oil paintings from them.
The permanent displays of art galleries and museums tend to offer much more exposure to paintings, with drawings from their collection only appearing during specific exhibitions. Those connected to these institutions maybe able to organise a browse through items not on display, but will have to arrange that personally. It is unfortunate that not all of these artworks are accessible, but it is inevitable when you consider that some venues have many thousands of items within their collections, and even by adding regional offshoots of their galleries, there is still not enough space to display all of them, all of the time. Loans to other locations can also help to freshen up displays and keep visitors returning time and time again.