[Goose]

A pretty thorough look at the Russian defense fortifications in this BBC report
 Ukraine war: Satellite images reveal Russian defenses before major assault

Wouldn't these fixed locations (trenches and artillery sites) be magnets for artillery and missiles?

Sure they will. However, where is the artillery shooting at these fortifications going to be? If it is sitting on the surface (like rapidly advancing forces will be) it too is a magnet for missiles and artillery fired from within the trenches. The ones in the trenches are protected from anything but a direct hit. The ones in the open are not. So, unless the ones in the open strike first with such overwhelming force that the protected ones are destroyed quickly, the ones in the open lose big time. That is why tanks exist, to carry their protection with them. However, in today's world, tank protection isn't all that great. So, the answer is air power and surface to surface missiles if you have them. These weapons are able to stand off and hit the trenches with relatively little danger to themselves. Guess what both Russia and Ukraine are short on.

Ukraine's better bet is to go around these fortifications/trenches where they can and cut them off. In places they have to fight their way through it will be costly if the defenders stand and fight. Ask the Russians who have been attacking Bakhmut about what happens when the defenders do stand and fight and you can't go around them.

[Goose]

A pretty thorough look at the Russian defense fortifications in this BBC report
 Ukraine war: Satellite images reveal Russian defenses before major assault

Wouldn't these fixed locations (trenches and artillery sites) be magnets for artillery and missiles?

Sure they will. However, where is the artillery shooting at these fortifications going to be? If it is sitting on the surface (like rapidly advancing forces will be) it too is a magnet for missiles and artillery fired from within the trenches. The ones in the trenches are protected from anything but a direct hit. The ones in the open are not. So, unless the ones in the open strike first with such overwhelming force that the protected ones are destroyed quickly, the ones in the open lose big time. That is why tanks exist, to carry their protection with them. However, in today's world, tank protection isn't all that great. So, the answer is air power and surface to surface missiles if you have them. These weapons are able to stand off and hit the trenches with relatively little danger to themselves. Guess what both Russia and Ukraine are short on.

Ukraine's better bet is to go around these fortifications/trenches where they can and cut them off. In places they have to fight their way through it will be costly if the defenders stand and fight. Ask the Russians who have been attacking Bakhmut about what happens when the defenders do stand and fight and you can't go around them.