When the inside of your freezer looks like this, then you know it is freezing as it should. There are a few centimeters of pack ice on the shelves and when you close the door you have to give it a kick, a shove, to close it properly.
Yes, it is time to defrost. The contents are removed, and all sorts of frozen objects suddenly appear. Some are indefinable as they have collected so much ice and snow their shape has been deformed. And the boxes with remainders of strange frozen objects that you will never eat after being frozen for at least a year. This is not to mention the frozen peas which now resemble an iceberg with green spots in the bag. When did I buy them? Cannot remember.
And so two bowls of hot water are placed on the shelves and lets forget it for a while, but no too long. You might suddenly have a river on the kitchen floor. However, no big problem. Now and again thumps and crashes can be heard as the ice dislocates itself from the bars and falls to the shelf below. Eventually all is well, you now have a fully functioning freezer with space for a new collection and the garbage can is probably full of those surprise discoveries you made on the way. You will even be saving money because the electric freezing mechanism no longer has to work so hard fighting the pack ice.
Remember the last time you did it and swore on oath that you would never again wait so long. Oh well, why bother. You notice when it is time to do it again, when you can no longer close the door because the ice is coming towards you.