Euro 2020 qualification get underway in March, and Williams thinks that the Nations League has helped his side prepare for that.
Wales' hopes of joining the elite of European football were ended by an impressive Denmark side, who won 2-1 in Cardiff on Friday night.
Captain Williams, looking ahead to the start of European Championship qualification in March, told the 'Daily Mail': "These competitive games have been good.
"No-one really knew what was going on when the Nations League was brought in.
"But it's been worthwhile for us because we're in a bit of a transition with all the new players.
"The last few camps we've got to know each other really well, on and off the pitch, and you can see the way the boys are progressing.
"It stands us in good stead to go into the (Euro 2020) qualifiers. We want to keep as much momentum as we can and try and qualify through that now."
Several of Giggs' exciting batch of young players are set to feature and gain more experience ahead of the European Championship campaign.
"I don't know if there will be changes, but it's a chance to extend this camp,' Stoke defender Williams said.
"At international level you're not playing week-in week-out with everyone.
"But we'll spend more time with each other now and play against a very good team.
"Losing to Denmark is nothing to get down about, they are one of the toughest teams I've played against for a while at international level.