It depends on which competition you are playing in, there are a lot of politics and underhanded issues in many competitions that is kept rather hidden from the public eye. Arts competitions by their nature are very subjective, there have been leaked results from international piano competitions that came out and we could see the scores all over the place, so there really isn't any mathematical accuracy that judges go through when marking and it is mostly their opinions.
For example the Rina Sala Gallo piano competition revealed the marks given by every member of the jury to every contestant. The publication was provoked by a jury walkout on the part of the French pianist Pascal Rogé, who claimed the result was being rigged by Italians in favour of their compatriots. I tried to find an image of the marks but it looks like much of it has been taken down. If I find it on my HD I will upload it or perhaps someone clever can find it, from my memory it was all over the place the marking from many different judges.
https://slippedisc.com/2014/10/let-there-be-light-competition-publishes-jurys-marks/In saying all this the more difficult pieces you play these pieces will show the many effects the piano can produce, if these tough pieces are played convincingly they should trump anyone who plays a much easier piece even if they play it perfectly. I would say the vast majority of judges would look at the situation in this way but again judging a music competition really isn't very accurate. When I listen to famous competitions the level of all the competitors are so high it really is stupid saying who is better or not, there should be better ways to judge someone. I reckon an easy way would be to get all the pianists to present a concert and the audience judges who they enjoyed the most.
Ive attended a number of competitions winners concerts and they were boring as can be, no personality, no stage presence, they just walk on stage, bow play, leave. These competitions winner really didn't have to struggle to get where they were in terms of building a performance career, they just win competitions and get propelled into it all.