Most groups give you a set number of days per year. Some groups let you bank, others don't. Some hospitals let you bank, others don't. My hospital allowed a maximum of two years worth of PTO to accumulate at a rate of 8-10 hours per two week pay period. This was pooled PTO, however, so it also covered your sick time and other leave. It's also been reduced over time- recently they dropped it to 1.5x annual, and now it's dropping to 1x annual as of 2017. That all really sucks, as the old policies let me do crazy things like take a two month vacation in Europe after banking three years of PTO. Policies were the same for any physician employed directly by the hospital as they were for non-physicians. Basically, working for a health care conglomerate can result in some painful vacation policies, particularly when you factor in not being able to take vacation when you want due to staffing issues and the like- you might only be able to swing two weeks in a row max due to staffing problems if you don't have a large department.
Most physicians get around 3-4 weeks of vacation per year. The historical average for some fields has been higher- anesthesia used to typically offer 6-8 weeks/yr, while radiology used to offer 8-12 weeks/year, but times are changing and those fields are getting hit pretty hard, with commensurate shortening of vacations.
If you're looking for a job with chunks of time off, the 2 week on/2 week off hospitalist gig is a thing that exists. Other options include doing locums, which are three months in length, typically, and allow one to take a break between assignments. Finally, many jobs allow one to take a sabbatical at some point, which allows one to take an extended leave of absence (usually unpaid) for self-growth or other reasons. Other methods that allow for flexibility are job sharing (some places allow two hospitalists to split one job, which nets you half the pay but gives you a 1 week on/3 weeks off schedule) and part-time work (the so-called mommy track that many jobs offer for parents or older partners).