Wales held a slender five-point lead at the start of the second half in a feisty match at the Millennium Stadium.
But 50-cap Shanklin’s knockout blow enabled them to cruise to a third successive victory.
Jones said: “We put a lot of work into the first period. We dominated for long periods and we knew we’d put them under pressure and worked them hard. We knew opportunities would arise as they tired.
“Thankfully Tom managed to pick off that long pass and that gave them a punch in the stomach and took the wind out of them. We didn’t look back and got on a roll.”
The 47-8 win equalled Wales’s biggest margin of victory in the tournament but Jones insisted Italy gave them a real battle.
Jones added: “In the previous two games, no one has beaten them by more than 10 points in the championship and that wasn’t a fluke so we knew they were a very good side.
“But we approached the game in the right manner, we didn’t give them any heart apart from losing the first try due to a sloppy line-out but we kept our composure, scored next and did the job.
“We’re trying to play more as a team and it is still a work in progress. But it’s better to work on your game when you’re winning than losing.”
