In the USA and I assume most other countries, policies are rarely passed one at a time; rather, they are usually passed in omnibus deals. While this can go overboard in the real world, I think this could be an interesting change to passing policies.
Perhaps at the end of each turn, all the laws you’ve chosen go into effect, with their PC being added together. The total PC cost may then be adjusted depending on the policies being passed. Raising taxes or passing a new tax is generally unpopular, but it’s easier to do so if the increased taxation pays for something. For example, increasing Gas Taxes and Road Construction costs, say, 10 PC. But, passing them together only costs 6. This can also apply to raising one tax/passing a new tax to lower another, doing the inverse, or maybe even doing something like decreasing police/military funding and laxxing gun laws.
Like I said above, passing deals like this would reduce the total PC cost, but going back on another part of the deal would impact Trustworthiness and have an even stronger impact on the perceptions of the groups impacted. If you lower pensions and cut back on income tax, but then later increase income tax, the negative impacts from the retired and socialists is twice as strong; why’d you cut back on pensions if not to reduce income tax?