Never ! Not say that you or anyone on this forum does this, but with over 95% of all accidents due to pilot error, this accident chain of events is simply inexcusable.
Ever done a W&B calculation for a C 152 for a typical instructor and porky student with enough fuel for a typical 2hr PPL nav flight?
The fact this sort of practice does go on. The fact that people
usually get away with it makes it to them 'acceptable'. The problem happens when as covered above, the grass is too long, the density altitude is high, the pilot skills are rusty, the engine isn't producing full power.. or more than likely one or more of the factors combine.
The fact it does go on is confirmed by simply reading the AAIB reports each year. There is always at least one of these accidents in the UK. I would rather guess that for countries where light aircraft are used far more for utility the figures are far worse. Strangely in many reports the overweight condition is mentioned but not even considered a contributing factor!