Laura makes sure she purchases air filters for her central HVAC system on the internet.
The reason she does this is because you can buy them in bulk and get one heck of a discount on them this way.
Most of the time when Laura orders the air filters for her central HVAC they arrive on time when the website tells her they will be arriving. However, the last time Laura purchased air filters for her central HVAC they were late arriving. As a result, she was also late in changing the air filter of her central HVAC unit. Laura was completely out of air filters because she ordered later than usual, and just her luck the air filters that she ordered for her central HVAC were also late in arrival. They were almost 2 weeks late. So that was 2 weeks that Laura had a used up air filter in her central HVAC unit. Gladly, it did not do any destruction to the central HVAC or the indoor air quality of her home. If Laura had let that air filter rest unchanged for another month or so, there may have been the beginning of some serious faults with the air quality, followed by her central HVAC starting to overwork itself. That could have led to a drastic HVAc breakdown and cost her money in HVAC repairs. Laura wanted to avoid that.