I re-read my thesis now and cringe!
There are long, waffly sentences that need serious editing. The diagrams look amateur. The structure of the thesis barely supports how I frame my ideas. It could be so much better – and this doesn’t take into account what more or different research could show!
My thesis will never be perfect. Your thesis can never be perfect. There will always be things you could make better, but that doesn’t you won’t reach a point where you’re done.
Before submission you have to decide what “good enough” means, then work to achieve that standard. At your viva justify your decision. Your examiners might ask for some corrections you didn’t anticipate (or some you don’t agree with), but they’ll largely be requests to make it as good as they can reasonably imagine.
And eleven years later you might cringe!
It will never be perfect, but through submission time, the viva and afterwards you will find a good enough thesis to contain your research. Keep going until you’re finally done.