An overreliance on the adverb “then” or on adverb phrases like “then proceeded” makes your writing sound less like skilled academic or creative writing and more like a police report. Police officers are notorious for writing in a stodgy, dry style, in part due to the fact that the purpose of a police report is to explain a (sometimes very complicated) series of events as unambiguously as possible and in part because they frequently have to write several reports very quickly in between other calls for service.
Academic and creative writers, on the other hand, have the luxury of time and tend to write about subjects that are slightly less dire than unsolved crimes.
With that in mind, try to avoid phrases like “she then proceeded to” or, more generally, try to avoid the adverb “then.” Sentences containing “then” adverb phrases can almost always be fixed by simply removing the adverb phrase.
Example 1: She then proceeded to open the door and let the cat in.
Example 2: She then opened the door and let the cat in.
Example 3: She opened the door and let the cat in.
The first example illustrates another problem that tends to come up with “then” adverb phrases: The action verb in the preceding example is “open” and is present tense (She is opening the door for the cat.), but the adverb phrase is past tense (then proceeded) and the mix of past and present tenses is largely responsible for the awkwardness of the sentence and could lead to ambiguity.
It is possible to have consistency by using the present tense:
Example 1: She then proceeds to open the door and let the cat in.
Example 2: She then opens the door and lets the cat in.
Example 3: She opens the door and lets the cat in.
As you can see, the first example still has the tense issue (The word “let” is past tense.) but in the second example we finally have consistent verb tenses. The third example, though, is the simplest and most straightforward.
The easiest way to solve these issues with awkward constructions and verb tenses is to simply avoid using “then” adverb phrases. The only time you really need it is when you are listing sequential events or in if/then logic statements.
Example 1: “Man wanted a home, a place of warmth, or comfort, first of physical warmth, then the warmth of the affections.” – Walden by Henry David Thoreau
Example 2: “If we increase x to x+dx, then y will become y −dy…” – Calculus Made Easy by Silvanus P. Thompson
N.B. Even L.E.O.s should follow these guidelines.