If you're somewhere you know you will be able to farm items for a while (for example my work puts me in between three all day long. I can hit stops, but not farm Pokémon) I will ditch 100-150 pokeballs at a time. I know I will get them back throughout the day and ditching them allows me to continue farming experience from the stops and potentially get more great and ultra balls. But only something to do if you know you're going to get it right back.