At some point pilots need a make a stand at the poor terms and conditions on offer in the UK generally. Unfortunately, I don't see it happening as the industry is too fragmented, and pilots identify with their aircraft or airline more than a fellow pilot working elsewhere. You don't see that with Doctors , for example.
In the BA/IAG case, the organisation has shown itself to be unwilling to negotiate further. It is pointless waiting any longer. A one month strike would bring things to a head, and make loss of pay/salary deductions easy to calculate. Essentially, it is only the same as 1 months unpaid leave, something that is increasingly difficult to get in BA.
I would be more than happy to continue striking until the end of the mandate, before balloting to extend it further.