Plaid Cymru said it backed the “principle of widespread 20mph zones” but “no one can deny that there have been widespread problems with its implementation from day one”.
Mr Skates said the cost of changing roads back to their former limits will be paid by the Welsh government, not councils.
Mr Skates also gave examples of road projects, in north Wales that would go ahead.
Last week, he confirmed that some roads would return to 30mph, following a backlash against the Welsh government’s controversial 20mph default speed limit in built-up areas.
The policy is not being ditched. But Mr Skates said on Tuesday he was “refining” it.
Outlining his priorities as transport secretary to Senedd members, he said: “The Welsh government continues to believe that 20mph is the right speed limit in places such as near schools, hospitals, nurseries, community centres, play areas and in built-up residential areas.”
“What I am doing now is listening to what people want for the roads in their communities, and pressing ahead with refining the policy and getting the right speed on the right roads.”
Mr Skates told Wales that between now and July the Welsh government will “listen to what people believe should happen”.
In tandem he said revised guidance will be drawn up “that will then, over July to September, allow councils to check that they are able to make changes to the speed limit on certain routes”.
He added: “In September the process of reintroducing 30mph to some routes where people wish to see it happen will take place.”
Mr Skates said he could “not give the answer as to how many routes” would change “because it’s largely going to depend on what people say, what people wish to see happen.”
“It’ll be up to councils to decide which routes and how many routes change back.”