Now to Martin's work.
The assignment was clear - in the first phase I expect you to work only on the roof and everything that is at and above the roof level. At the same time I recommended that you use a maximum of 1/3, ideally 1/4 of the texture for this part.
The texture should be rectangular. You failed to follow any of that. On the other hand, you were the only one who sent me (correctly) an FBX. The others sent a cat...
I return to the above-mentioned point 3 - understanding the assignment. I appeal to everyone to read the assignment carefully. If you do not understand something, ask questions (point 2), because only in this way can you successfully complete point 1 - meeting deadlines.
I will evaluate what I received from you.
Pixel density is OK, regarding uniformity. Mapping on the roof is bad - the texture will be distorted. 
You made a square texture instead of a rectangular one. Now it's starting to become clear why the rectangular texture is more useful.. right? I estimate that 2/3 of the texture is taken up by the roof + turrets. How do you want to map the rest of the castle?
Notice how many identical elements you have on the texture. Each duplication takes up precious space and thus reduces the pixel density. Use everything that is repeated in the castle only once in the texture. You made three separate roof coverings completely pointlessly. Why? Because they are exactly the same. Instead, you could have drawn one continuous repeatable strip of covering in the upper part. You have it interrupted, so you can't draw the UV and use the repetition. There are huge gaps between the individual elements of the texture. That is completely pointless. Fit everything tightly together. Don't use black as the background color, but one that corresponds to what is on the texture - where there is a roof, use red, and where there is a wall, use ochre.
I have reworked your link to show you all how to do it with a practical example:
Two almost identical towers. The one on the right is yours. The one on the left is mine. They look almost the same. But the model is different:
Why? So that I can use the texture effectively.
Your model + your texture:
My model + my texture:
All three windows in the middle use the same texture. In the lower part I made a repeatable wall texture, which I will use later on all the walls of the castle. Remodeling the turret + making a new texture based on Martin's texture + new UVs = 30 minutes of work.
I am sending you the text and the texture in the attachment. Please take a good look at it. I can't give you a better answer for this task.
Martin, you are still in the initial stages of texturing. With the texture you sent me, you will soon reach a stage where you will find that you have to redo it completely. Simply, you will not have enough space for the texture. The pixel density will be low. I recommend that you analyze the model well, and arrange the texture correctly, and reduce the elements so that they do not have to be repeated on the texture (windows, doors, cornices, etc.). If you want, you can, but you do not have to mess around with pebbles, window frames, and unnecessary details now. Just indicate them. They can be detailed at any time later.
I would recommend making a working texture like this:
Colorize individual elements, and put a fine checker over the entire texture so that you can control the density. Gradually add the necessary elements to the texture - there will definitely be some skylight, some strip with cornices, doors, etc. Define, for example, that the repeatable skylight strip will be on top, the plaster strip on the bottom. Give them the right density, and push everything else that will not be repeatable between these two strips. Save it like Tetris - so that there are no gaps. If you have some free space left, don't worry - it can always be used for some details. Then cancel the color overlay and checker, and start working on detailing the texture.
Please focus primarily on the roof, skylights, and chimneys.
As always, if you have any questions, write.
