Yes, it is OK to pull a lawn mower backwards but only when you’re mowing a small patch. When a patch of grass is very small, it makes it awkward to turn around with your machine. So, we move in and pull it back. And we repeat the process until the grass is cut.
Pretty laser lines on small patches of lawn don’t even show up properly so we need not stress. If you try to turn around with your mower, you will most likely step into planted beds and cause other problems.
Larger lawns are a different story because mowing backwards makes it extremely difficult to cut in straight -laser!- lines. You will inevitably lose the lines and either:
a) Create “mohawks” or uncut sections of lawn surrounded by cut lawn. A week later these mohawks become pronounced and detract from your clean cut lawn presentation. Fixing them takes time.
b) End up cutting sections twice which is a duplication and a waste of time.
Well-cut lawns have beautiful straight lines and this is accomplished when we push the mower, not pull it. Pulling your mower means that you’re not looking at the lines properly.
Another problem is safety. Mowing backwards means that the mower is moving towards your feet not away from them. One slip or hesitation and your foot could end up under the mower deck with potentially severe consequences.
Mowing backwards is also much slower than pushing the mower forward. It’s hard to get a good rhythm going when you mow backwards. Pushing the mower forward the way it was intended allows you to build speed and force while staying on course.
So, if your lawn is too tiny to allow for full mower turns, then by all means push it in and pull it out until it’s done. On larger lawns it doesn’t make sense to mow backwards. Finish your line and turn around properly so you’re correctly line-up for the next pass.