The National Union of Teachers believes it is winning the argument with heads over the introduction of teaching and learning responsibility payments which could lead to salary cuts of up to pound;10,500 per year.
The union has held action, mostly one-day strikes, at 14 schools where its members were unhappy with proposed staffing changes. It had expected to hold strikes at about 50 schools, but now believes that negotiation is resolving many of the disputes.
However, the union this week launched indefinite strike action at Heaton Manor school in Newcastle in protest at changes which led to pay cuts of up to Pounds 3,300 for about 17 teachers.
The action, which will force more than a thousand pupils in Years 7 to 10 to remain at home, went ahead despite an increase in the number of posts attracting an allowance from 67 to 75.
John Dryden, headteacher of Heaton Manor, said: "Unlike some other schools where industrial action has already taken place, we have not replaced teaching posts with support staff."
NUT members have formally voted in favour of action at more than 30 schools, with more than 260 holding informal ballots, intended to put pressure on heads into making concessions.
John Dixon, NUT assistant secretary, said the union was hopeful it could protect members from salary cuts of up to pound;10,500 with fewer strikes than expected.
He said: "I am pleased with the progress. We are getting resolutions in an increasing number of schools. It is looking like the number of heads who are not prepared to reach a resolution might be limited."
The more positive outlook from the NUT comes as the rival NASUWT is holding ballots at five unnamed schools in Manchester, Derbyshire, Merseyside, Lancashire and Caerphilly.
The NASUWT, which has so far kept a low profile over the issue, is threatening action despite being a member of the Rewards and Incentives Group which agreed the changes with the Government.
Chris Keates, NASUWT general secretary, said: "The statutory requirements and the nationally agreed guidance for implementing the revised staffing structure and pay provisions couldn't be clearer. Yet there are still schools failing to follow them.
"It is utterly frustrating that it is necessary to resort to industrial action before some schools will give teachers their entitlements.
"The NASUWT has made it crystal clear from the outset that, with the support of members, the union will take action to ensure that the agreed provisions are implemented fully."
Ms Keates said primary teachers faced particular problems, with some headteachers expecting them to take on additional responsibilities without additional pay or to continue undertaking tasks which previously attracted a management allowance but without being awarded a TLR.
It remains to be seen whether there will be a further round of disputes in Wales. Welsh schools have to finalise new staffing structures by March 31.