The ACA wasn't negotiated in secret. Budgets are normally continuing resolutions; they only negotiate the delta from previous years, which is usually small. And again, budget negotiations don't involve years of secret negotiations.
Same with respect to full budgets - they're long, they're complicated, but the period during which they're publicly available is on a similar timescale to this 60-day period.
I did not say that continuing resolutions are an ideal. My point was that although budgets are complex, only a relative small part of them changes from one cycle to the next. People don't have to digest the whole budget, because they already know what was in it before. They only have to understand the changes.