I sometimes wonder how many people pay any attention to warnings about adequate ventilation for equipment. Stuff gets stacked up on top of each other, then something gets laid right across the top items completely blocking the ventilation slots.
Another problem these days is the ever-growing tendency to use the cheapest component possible. On a large production run, there's always been the requirement to do this to keep costs to a minimum (and therefore profits to a maximum), but the problem is that components are being much more generously rated than in the past.
Just compare the physical size of a 1/2-watt resistor now with a resistor of similar rating from 30 years ago.
