[Google Pixel 3 XL Questions & Answers] Qui Peccavit:
Doing it right once is better than doing it half-baked a hundred times

Quoting posts in their entirety is not necessary when the one you refer to is just one or two above yours, i.e. repeating the parts you are referring to is suficient.

Second, as with so many topics on this board, the question may have been covered many times, but usually in the same superficial telegram style without details or references as above ― which is the very reason why the questions are repeated in the first place. If there was a reference link to a detailed, step-by-step instruction that explains the necessary operations (where to find the tools for unpacking and later repacking, etc., etc.), people would not have to ask again, until one day somebody provides a comprehensible and complete, detailed step-by-step instruction. Such a guide does not have to be rewritten each time the question pops up, but «has already been covered» without doing so and without directing people to the relevant information is not as helpful as it could be. :)

It's like with rooting, patching, jailbreaking and other threads here on XDA: Some geeky nerd cannot write three structured sentences in a row or is too lazy to explain the procedure step by step, rather throwing around buzzwords and mentioning things without links so that people then have to hunt down a hundred tidbits from a hundred places, and in those threads, it's incomplete, superficial gibberish just the same. This is no exaggeration: there are threads here about doing something rather simple, but because the guy who started the thread was too lazy to invest the last three hours that were needed to patch it completely and fixing the known issues once and for all, too vain to wait with publishing until that has been done and too verbally incompetent or lazy to explain it properly, there are now 650 posts in that thread because god beware if somebody dared to tell the nerd «try to talk in proper sentences and explain it step by step». Many, many people wasting time, nerves, energy and work to figure something out over months that could be done by anybody in half an hour, if only instead of the imprecise mumbo-jumbo in the first post and three-word answers to questions, the geeks would do it right once in the beginning. This is speaking in general terms, not directed at any one person in particular.

Lastly and referring to the particular issue at hand, of course one can always go through the entire procedure from scratch, i.e. flash a stock ROM, re-root and do it all over again after the next update every month. The question was more in the spirit of «how can a rooted phone be updated without having to run through the entire obstacle course each and every month?», i.e. keeping the configuration, apps, etc., similar to the way it would be if the phone was not rooted. Flashing the new firmware is no problem, but having to do all the installing and configuring afterwards each time is something that, if it can be avoided, would be nice to avoid. :D

Again, this is not directed at you nor anybody else in particular, just to explain and maybe ring a bell that when questions are repeated over and over again, the previous answers cannot have been so terribly great, can they? And if they were, why not provide or link to them, instead of teasing with «has been answered already»? ;)

Edit:

As already stated earlier above, the question has been moved to the proper location. Therefore it can/should be ignored in this thread, but taking the general considerations above into account in the future cannot hurt, can it now?