The Welsh international was a regular starter for much of the campaign, one which had been expected to be one in which Everton pushed for a place in the top four, but he didn't feature after betting sent off against Burnley in early March.
The 33-year-old served his suspension but was not recalled by then manager Sam Allardyce and he is now looking ahead to next season when he will be working to impress a new head coach.
Williams was speaking to the media ahead of Wales's friendly against Mexico in Pasadena.
"Yes, definitely," he said when he was asked if 2017-18 had been frustrating for him personally.
Williams added: "But that season is done now and I'm just looking forward to this game and into pre-season for the next campaign.
"It's always difficult not being involved and you want to play because playing a game is that bit harder.
"But what can you do? I've just tried to stay in shape and on Monday I'll just try and use my experience as best I can and play as well as I can."