I'm only guessing, but for what it is worth...
Say for example, there was one job position and there were five applicants of whom three were suitable. They would offer the job to the most suitable first. If that applicant declined due to salary, they woud then offer the job to the next most suitable and so on. If none of the suitable applicants take up the offer, then they might increase the salary and start the offer process again or they might re-advertise for new applicants or they might lower the standards required to include the previously unsuitable applicants.
Depending on the variables, this could take some time...
You could make it easy for them and yourself by telling them your minimum acceptable salary. And be prepared to walk away if they don't come to the party. The job is only worth having if the rewards outweigh the pain.
Good luck!