Recently I found Quake 4 on my hard drive and I wonder if this entire Single Player map was created in editors like Radiant, Quark, etc.? After all, there is a lot of variety and detail, even from bullets, the marks on the walls vary depending on the type of material. Doing something like this in these editors is significantly time-consuming.
Quake 4 uses idTech4, aka the Doom 3 engine. The levels were made with the built-in editor which I understand is a continuation of Q3Radiant. So yes, most of the levels have been made in a Radiant-like editor. I do think a significant number of props and assets have been modelled in a dedicated 3D modelling program like Blender or 3DSMax and imported I to the game. Quake 3 (idTech3) already allowed this and was done to some degree. Quake 4 will have expanded on this.