A spec script (spec is short for speculation) is a script that is written by a Writer who is (alas) only hoping it will get made; that means there is no fee waiting at the end of the draft.
Though it is important to follow formatting rules, a spec script is written to engage the reader, so it should flow from scene to scene without jarring statements like what we see or what we hear.
When you read a novel, nobody needs to tell you to visualize. You just do. All it takes is good, concise prose. So, as a general rule, there is no camera direction in a spec script, nor should there be any transitions such as CUT TO or DISSOLVE TO.
Why? Because camera direction is the job of the Director and the Cinematographer, and transitions and when to cut is decided by the Editor and the Director. The only time you should see a transition in a spec script is FADE IN and FADE OUT.
Most scripts that are available online are shooting scripts, so many newcomers read these and think they are a good model for spec script writing but they really aren’t.
It is not the job of the Writer to decide what kind of shot serves the moment or how to transition to the next scene. You’ve got enough to do!
It’s the Writer’s job to tell the visual story so the Director can imagine it herself. Of course, it is the Writer’s job to visualize the story and must use their subtle and magic writing skills to inspire the Director to put on screen what they have in their mind. That’s the craft.
Credits are another thing that don’t go in a spec script. When you toss in something like “roll credits” in the middle of a scene, it takes the reader out of the story… or worse, they think the script is the work of a hack.