If you listen to Muzz's suggestions you won't have a problem, especially with the texture scales and func_illusionary + clipbrush complicated stuff to give you more clipnodes. (the only part i vary on is i always use
cliptype simple to get the most clipnodes)
I'll take a look at the map too, but i think Muzz covered everything
- 2 or more brushes that are in the same entity group meet.
totally, but sometimes you can get away with it without a problem. sometimes you run out of the number of solid entites you can make so you have no choice to group them together. I actually do it all the time as long as there is no visible visual errors.
a good example is if you have 2 pieces of fence butting up at a corner and they are transparent textures. if you make both of the pieces of fence the same entity, you will get splitting or be able to "see through" or HOM effect on parts of the fence. Making the fence walls individual func_wall entities fixes this as muzz was saying.