Most people beat themselves up post-interview. Although I encourage people to self-reflect post-interview and to record a few bits down at to how they felt things went, the problem with this is the vast majority of the time people only focus on the negatives of this rather than being really honest about what went well and what didn't. The focus too much on the negatives and hang on to them - that isn't a good thing to do.
Even if it is an unsuccessful interview, think about what you can take from the experience - that at least will be practice and learnings for the next assessment.
However, I have lost count how many conversations I have had with people who will literally beat themselves up about the smallest of detail - they overthink about what they said, what they should have said, how they could have said it better, how one assessor seemed really grumpy and they thought that they didn't like them as a candidate, how the questions were really challenging and wish they'd been better prepared for them etc etc etc. That includes someone on here who recently got a TC with a very reputable firm. We had a series of messages back and forth after their interview where if I took purely how they felt about it, you would have thought there was little to no chance of securing a TC. However, I knew the realities of what they were saying and how they were over looking the positives of what had happened and were just second guessing how they had been perceived.
Take some time to think about the positives - write them down even. Even if it was a disaster of an interview, you have learnt something from it and that is a positive
