To really answer this question fully, I really need to know how you set up on the bench.
1. How is your arch?
2. Where is your foot placement?
3. Are you able to keep your shoulder blades together, and lats tight?
4. Are you brining the bar down with the lats, or are you losing your arch?
5. What is your bar travel on the way up? Is it straight up, or is it in an arch?
The bar travel will not be perfect every time, but you need to know what your strongest groove is. You are right with the concept that there is no need to add bands/chains untill you can move the given weight as quickly as it needs to be. Its not about how much weight you move, but more about the explosiveness you complete the lifts with. To give you a reference point, I use 205 when I am doing some Dynamic effort work. I have benched well over 700lbs in a shirt. Most people are shocked with the amount of weight you can add to your benchpress in just a few weeks of working on set up and form.