Using a dispenser in combination with a sculk sensor doesn't trigger in some situations where a dispenser 'fails'.
- Flint and steel when no fire is placed
- Bonemeal when no plant is grown
- Heads/carved pumpkin are failed to be placed/equiped
- Shulker box failed to be placed
- Shears fail to shear
- Glowstone fails to charge a fully charged respawn anchor