Adding lights question

Do I need to re-compile eveything if I want to see if a light is going to work for me?

I re-compiled my project, and everything became pretty dark, or totally black.
So I turned of Lit, so I could see the scene.
I added 1 spot light, and didn’t see any difference, since it was asking to re-compile.
So it’s recompiling now, and takes about 30 min,

do I need to do this, just to see if the lightning is ok etc?

This is going to take days to get the lights in place, and i need to recompile every time.

2nd question, I add emissive to my lamps,
But I cannot get the effect to work as shown in the video (Unreal Engine 4 Emissive Material - YouTube) around 2:54

I looked at other videos, and they are all doing the same thing, but for me it’s just a white ball, I can only keep the color between 1 - 5, otherwise it turns white.
I am missing the whole glow part.

Thank you

There’s some preview shadows that it can show when you place a light but ultimately you need to build the lighting to see what it will actually look like because it can’t preview things like indirect lighting or how your lightmaps will look.

Thank you.

Do you know about the glowing issue I am having ? for the 2nd question?

Thank you