ZXX3200.1D driver board 1D-2D replament

I have a Hifonics ZXX3200.1D with a failed power supply.
My question is in reference to this thread https://www.diyaudio.com/forums/car-audio/346991-driver-board-repair-help.html
referencing the replacement of the 1D and 2D transistors on the output driver board.
I typically add heatsinks to the Hifonics cards where the 1D and 2D transistors are located closer to the middle of the card.
The 1D and 2D's on this card are at the top outside corners. Less heat soak perhaps?
To aid in reliability, would it be good practice to include a heatsink to both sides of this driver board? Or by design do these stay cooler and no additional modifications needed?
 

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They don't run as hot as on the 11-pin boards but they have a relatively high failure rate. Whether you add a heat-spreader or not would be a judgement call and may depend on other variables like the duty cycle of the amp (does it get played 10 minutes at a stretch or for many hours at a time) or the climate where the amp is being used.

As a side note, the replacements rarely fail. Maybe they're so close to the margins, the extra solder that's used in hand soldering makes a difference. Maybe the replacements have been higher quality?