When a buyer is interested in purchasing a property and waits, it's the laws of nature that someone else will bid and make that property pending. "Pending" means that a buyer submitted a bid the seller has accepted the offer or they have came to an agreed price on the property. This is when the process of moving forward on the inspections and financing begins. From time to time the property will go back on the market due to the buyer couldn't get the financing or they found something during the inspection process that was not acceptable. Other buyer can submit back-up offers on the property to let the seller know if something were to happen they have another option.
The fact is if you are looking at a property and really like it, move forward on a bid. Because if you like the property there is a good chance someone else will also like the property. It doesn't matter if the property has been setting for a week, month or a year, it's the law of "it went pending".