GREEN BAY, Wis. -- When ESPN's three days of live draft coverage finally goes off the air Saturday evening, 256 players will have been drafted.

But player acquisition will be far from over.

In fact, some NFL personnel executives have said the most stressful part of draft weekend is the process of signing undrafted free agents as soon as the seventh round finishes.

In a matter of a few hours, some teams sign as many as 20 undrafted rookie free agents. It's a process the Green Bay Packers take seriously. It's why they use many of their allotted pre-draft visits on players likely to go undrafted. They consider it part of the recruiting process.

But they aren't the only ones who actively recruit potential rookie free agents. The Seattle Seahawks distributed a 12-page brochure to agents showing them how the team covets and strongly considers undrafted free agents for its roster.

Among the charts in the brochure is one that shows preseason playing time for undrafted free agents and another with the percentage of undrafted free agents who make the 53-man roster.

In terms of playing time, last preseason, the Seahawks led the league in playing time percentage by undrafted rookies at 36.2 percent, according to their research. The Packers were second at 33.6 percent.

On that page, the Seahawks noted: "If your client doesn't get on the field in the preseason, he'll have a tougher time making that team's roster or any roster at all. Last season, the Seahawks ranked No. 1 in total offensive and defensive playing time by undrafted rookies."

When it comes to making the roster, the Seahawks said 22 percent of their undrafted free agents since 2010 have spent time on their active roster, which ranks eighth in the NFL, and according to the brochure, “the Seahawks have been selective in the number of UDFAs they sign each year. The team has signed 68 of them, which ranks 17th."

The Packers actually have a higher percentage of undrafted free agents who appeared on their active roster at various points during the season since 2010, according to the chart, at 24 percent, which is tied for fourth in the NFL.

The Packers have had at least three undrafted free agents make their opening-day roster each of the last four years. In that time, 13 undrafted free agents have made the Week 1 roster, which is tied for the third most in that span behind only St. Louis (17) and Cleveland (16), according to the Packers.

Here are the undrafted free agents that have made the Packers' roster coming out of training camp the last four years:

2013: S Chris Banjo, OLB Andy Mulumba, Lane Taylor.

2012: T Don Barclay, WR Jarrett Boykin, OLB Dezman Moses, S Sean Richardson.

2011: S M.D. Jennings, LB Jamari Lattimore, OLB Vic So'oto.

2010: G Nick McDonald, CB Sam Shields, OLB Frank Zombo.