On our site I've noticed that most people use far to many slug pellet...the ground is almost blue from them...
I keep dropping hints that one only need few to do the job. In fact I saw on one manufactures site helpful advise...4" space between each pellet is enough when scattered around.
When I used to use slug pellets bit more I dropped 2 or 3 per plant with wide spacing plants like brassicas, one would struggle to see them but they still did the job.
My current bottle of pellets I've had for 5 years and the way I carry on, it will last
at least another 5 years
If my plants start to get too much slug damage...I rather pay little extra and get nematode treatment for the land. It works and if done correctly it keeps things under control for few years
Sadly slug pellets are one of the best selling products in our lottie shop...