Similar to the default option for splitters, a large number of the inserters I place (maybe a third of my inserters) set a filter for ash, either a whitelist or blacklist. I use the mod setting to set a default item on splitters, and would love an equivalent option for inserters.

The smart filter does work, but I usually don't use it because the inserters tend to swing once or twice before I get them configured which sometimes pollutes the output belts. Instead I place the inserters away from the building, configure them, and copy & paste them into position.

(Ash is a pyanodon thing... most of your buildings and machines are burners for the first 50-100 hours and most fuels burn into ash which must be removed, meaning you need filter inserters when outputting from most machines)