To be honest, i'm actually wondering if it wouldn't be actually possible to do so, though i'm fairly certain the fuel flow amount prevents such a thing.
supposedly they are limited to 4 or 5 engines during a season, if they don't comply, they 'simply' get a grid penalty.
the question then becomes, what if we decide to raise a finger to that regulation, and investigate if building one engine for each race could be worth it, if it can bring enough
gain to compensate the grid loss.
Again, the fuel flow regulation surely prevents that, but knowing the engine is 'compromised' in certain areas since they must live longer, then one could argue that you could
make the engine lighter, and a tad more fragile, and make for example the turbo spin so hard, have the exhaust so hot, have everything on such breaking point (ala colin chapman theorem),
that when the finish flag is waved, it's done it's job and allowed to crack. there's surely a benefit there to be made, question is, is that benifit big enough to compensate the penalty?
If i'm correct, any usage of a 5th one of any engine-related object, will give a 10-place grid penalty. that also goes for the 6th one. I'm not sure whether that means that for example. they completely destroyed their entire unit for spain when the finish flag drops, then they'll mount a new engine for Monaco. that includes the MGU units, the Turbo, the ICE, etc.
will they 'only' be given a 10-place grid penalty, or will they ALSO get another 5-place grid penalty for the MGU/Turbo etc. meaning; a 15 grid place penalty or a 20 place grid penalty?
if it is 'just' a 10-place grid penalty, that would mean that if they are able to get P1 during Qually, Alonso would start from P10. he then has to make certain power to be able to pass the 9 cars in front on speed/power alone. If he gets a total grid penalty that leaves him up to p20, then he must have a car/engine that is able to compensate those 19 spots in front of him, that's 10 spots more to compensate.
offcourse the engine also must be homologated.