I don't believe none of us need every update unless it pertains to our particular area or areas we visit. I'm just one who always likes the latest of anything like this, but I may slow down.
One thing to watch out for if you apply every update is that flash memory has a limited number of write cycles it can go through prior to it beginning to fail. If you update rarely you'll probably never exceed this limit, but if you update every release (and then do some customizations to your scan lists) you could easily exceed this limit sooner rather than later.
If you update often it may be a good idea to get several SD cards and rotate them as you update. That will also give you a backup of the last few updates so if one happens to cause issues, you can quickly swap them out to the previous update's card and be back in business quickly.
It's somewhat difficult to figure out exactly how many write cycles an update will burn through without knowing exactly how that update process works. It may simply overwrite the existing data and be a single cycle. It may clear out the existing data and then write the updated information back to the card (this will be at least two cycles, possibly more). It could even update only the data that has changed so only the spots that hold that changed data will have a write cycle, not the entire card (or more accurately the area on the card that holds active data).
There are advantages and disadvantages to each method. Some will do the update faster, but may perform more slowly others may update more slowly but perform faster. Some methods may be more reliable than other methods. There may be some methods that will leave spaces in the memory card so it will take up more room. The maker of the scanner and update software will select the method that they believe will be best for the process and market.