Regulatory change is the normal state of affairs when there are changes of government. But the extent of this change will depend on how different parties A and B really are. If ideologies are set to one side and there is a pragmatic centre ground of only minor fluctuation, then change will be slight, which has the advantage of mostly everyone knowing where they stand. Institutions, organisations, societies generally abhor upheaval and uncertainty. They like things as they are, but they don't always stick to this line of thinking. Change is deemed necessary.
In football, to use a trite example, you can get situations such as Crystal Palace. Upheaval, essential in order to keep the filthy lucre of the Premier League flowing in, means the booting into touch of an Alan Pardew fannying around and going nowhere (except down) by the heavy boot of a Big Sam. He may unfairly be characterised as a Route One advocate, but let's accept that he's sort of Route One and a Half, whereas Pardew was Route M25, going round and round in circles and unable to see light at the end of the Blackwall Tunnel.
To return to politics, ideologies do of course hold sway. Party A adheres to its set, as does Party B. Ne'er the twain do they therefore meet. Which would be simple enough to understand, except when there are Parties C, D, E, F and possibly G to take account of as well. Among this array, there will be voices which insist that they are not engaging in ideologies and are being pragmatic. Which is a load of nonsense. It is pragmatism that suits the party which is declaring it, as also does the constant cry of consensus. This is fine so long it's my consensus and not yours, which doesn't make any sense but can do when one or other parties are browbeaten into finally giving up arguing and going along with the consensus for the sake of a quieter life.
This is the situation which exists within the Balearic government, in the Balearic parliament, at the Council of Mallorca and at the town hall in Palma (as well as some other town halls). On the ruling side there are PSOE, Més and Podemos, with Podemos either formally part of the administration or not. Each has its ideologies, with Podemos having the oddest. They are, as often as not, ideologies of putting a spanner in the works just for the sheer hell of it. Normal rules of political protocol don't apply.
On the opposition side, there are the PP, El Pi and the C's (plus Party G in the Balearic parliament, the Gent per Formentera, all one of them). Each of them, with the exception of the Gent who ideologically aren't anywhere near the other three, occupies territory of varying degrees of right of centre. Of them, El Pi can be the most contrary. It does rather depend on which part of its regionalist-nationalist inner ideology happens to be dominating on a given day.
Which brings us to how change comes about. El Pi sided with the left in pushing through the change to Mallorca Day by the Council of Mallorca. Yet previously, when its chap was heading the Mallorca Day committee before he resigned because no one was listening to him, it had been on the side of keeping 12 September. There must have been a realisation that on ideological nationalist grounds there could be no alternative but 31 December, so the votes were duly cast.
The PP, also divided on inner ideological grounds, has said that it will change the day back again. And why would they do that? Well, because they'll be able to, one supposes. Because they've opposed 31 December, there's no better reason to later revert to 12 September. Personally, I believe 31 December makes complete sense, but sense is not what we're talking about. It's ideologies which matter along with the impulse to change things just because you can. Més say that 31 December will be better because the citizens will take more interest, which is further nonsense. The citizens won't. Theirs is a justification raised so as to disguise ideological motives.
What else is batted across the political ping-pong table? The name of Palma is one. The PP, aided and abetted by the C's, will add "de Mallorca" once more. Why? Well, because it's practical to do so, which may be true but is also right-wing speak for saying we don't like what the left are doing.
And so the list goes on, no one ever quite knowing where they stand. One side says Catalan, the other side says Castellano, so changes the rules only for them to be changed back again. Everything changes because it can be changed, even current governmental agreements for change. Just ask the ideologues of PSOE, Més and Podemos.