Yes but at any given point in time it's always the case that change X will generally favor party Y and party Y's states aren't going to favor for change X. They won't vote for it and if they previously had that is likely to be undone.
Absolutely. Every change picks winners and losers.
That's the story of politics. The electioneering never stops.
The last 16 years (to pick a time frame) Republicans have been masterful at moving the needle to favor them. And it's worked. They punch way above their weight. But a correction is inevitable. And it'll hurt.
Just like how the left peaked in the mid 70s, kept power for a while longer than the country supported them, and then had their teeth kicked in.
But what rubs me about all the electioneering is the emphasis on the mechanics. There is a third player: the voters. Fair redistricting, publicly financed campaigns, universal voter registration, etc. would all favor voters and piss of the political parties. Because the candidates would have to focus more on platform and policy, less on GOTV.