Time to create a map is different from everybody. I am one of the fastest mappers you'll meet. I can create most maps in a day or two, but then I am a professional and create dozens of maps each month. Some people take weeks to do one map, it all depends on your familiarity with software, the understanding of techniques and knowing what you want ahead of time.
Software is just as individual. Even if you think GIMP requires a graphic arts degree, it doesn't. Just follow the tutorials in this forum and you'll learn GIMP for your needs right quick, but you have to follow the step by step tutorials to 'get it'. Sure is complex, but simple software is generally too limited. Campaign Cartographer is a great suite of programs, but it is CAD and it does have a steep learning curve. If you want to make maps quick - I think you're better off doing the tuts for GIMP as GIMP is free open source software.