People tend to think in squares or straight lines. I remember a junior high school art teacher who asked her class to draw a line. Twenty-eight out of the thirty kids (me included) drew a short straight line. Only one drew a line that had a curve and another drew a circle. That is probably why when you look at pasture fences they tend to be squares of different sizes.
For pastures this is not always the best answer. First of all, if you turn your horses out together an aggressive horse can easily trap a more timid one in a corner or keep them away from water. This doesn’t mean that all your fences must be circles or maze like but being aware of it can help you from making costly design mistakes. If your fence follows the contours of the land instead of going up a hill it will go a long way to helping to prevent erosion. And always use your pasture fence to keep horses out of a stream whenever possible – as tempting as it is to see them standing in the stream or splashing in the water.
Secondly, when designing pastures keep in mind how many times you will need to walk out to them. Even if you use turning your horses out as your way of getting the recommended 10,000 steps per day, keep in mind that you may occasionally have to leave your horses in someone else’s care and having an easy to work efficient system will make it much easier to find help and will cut down on the margin of error. If you design your pasture in a wheel shape with all the gates meeting at a central heavy use area it can make it much easier to catch and lead two or more horses at a time, as well as save you lots of steps.
If you think you might have stallions on site or even if you have a grumpy old gelding or mare who like Garbo “wants to be alone”. You might consider leaving alleys between pastures. Always make sure you can fit your mowing equipment along them or you will be spending a lot of time with a weedeater in hand. Most importantly, and this is something I see forgotten a great deal of the time, ALWAYS have a perimeter fence on your property – because horses have a habit of getting out when you least expect it and it is better to find them in the back 40 than on the highway.
These websites have some good information about pasture design