Hot pepper sauces and steak sauces have semi-solids that collect in the neck of the bottle just below the opening. To ensure getting every morsel of the contents, when you start noticing the clog, invert the bottle upside down in a dish rack or prop upside down. Shake a few times before inverting. The liquid will reabsorb the solids. You will need to start doing this when the bottle has half or less of the contents remaining.