You can add trash until the compartment is full and the compactor will not compact the trash any further. The compact cycle time will be shortened as the compartment fills up. During full cycle the ram travels 2/3 of the way down into the trash bucket.
With Humalog's short action time of 3  hours, covering postmeal highs with more insulin can be considered as soon as two hours if a meal dose have been underestimated. Of course, not as much sliding scale insulin would be needed here as before a meal, because some of the meal dose is yet to work.
I give myself about 21 units of insulin per day--13 units of Lantus and a sliding scale of Humalog between 6-10 units--depending on how many carbohydrates I have eaten--So, it takes me about 2-3 months to use a bottle of Humalog and the Lantus would take longer, but I must open a new bottle every month for consistency issues.