There are a ton of different opinions on spay/neuter. I think it just comes down to an individual's situation.
There are a ton of interesting articles out there about the benefits and risks of spay/neuter at different ages in dogs, I recommend you do some research if this is an area of interest.
I think it depends on many factors such as breed, health of animal in question, etc., not to mention, if you can keep an intact animal from reproducing until it is altered.