A scrape is like a sign post for deer.
The sign tells the other deer the sex of the deer making the scrape, the physical condition of the deer making the scrape, even tells the other deer which deer made the scrape.

Scrapes only works in the prime of the rut when the deer are making a scrape to show the does - here I am girls, come and get it.
A scrape can often times be visited by a rival buck which will come and try to erase the previous owners scrape and cover it with his own scent and urine.

A scrape is not a permanent sign and the deer will make new scrapes every year in different spots - so just knowing where one was at last year is not good enough to be a spot where you hang your camera's this year. In Pennsylvania, deer will not start to make scrapes or visit them until the rut which will probably be in about 4 or 5 more weeks.

The rut is determined by the phase of the moon and the time of the year and the menstrual cycle of the does in the herd in the area.
When you have many does and many bucks, you will see many scrapes.
When you have many does and very few bucks, you will see very few scrapes. When you have many bucks and very few does - you will have very few scrapes and the bucks will travel in bachelor groups.

When the rut is over, it is nothing to see 3 or 4 bucks traveling together.

A doe if not impregnated, will come in heat again the next month and continue to come in heat until a receptive buck comes and mates her. So even if you shoot a nice buck, that does not guarantee you that he has or had not yet spread his generic's.