Having separately elected house, senate, and president is a primary source of gridlock. Each body can reject a legislative change, while none can effectively create change. The only way laws can be passed in this system is under a very rare set of conditions. When those conditions are present (government shutdown imminent, filibuster eliminated, plurality requirements reduced) you see large omnibus bills pushed through as fast as possible, without time to adequately vet the details.
From an engineering perspective, this would be like pushing a few massive commits every few years rather than making regular bug fixes as needed. As such, our laws are buggy and unmaintained. Unfortunately, this leads many to believe that regulations generally are ineffective rather than the poor implementations of such being ineffective.
Poorly written legislation puts more pressure on the judicial system to litigate between the lines. This is an externality that is extremely expensive for every individual and company to have to deal with.
I advocate for a more parliamentary style system where politicians continued careers are based on their effectiveness and continued approval rather than fixed terms. There are plenty of ways to ensure proper checks and balances without stopping government dead in it's tracks.