In section 2 of his work, Tempora und Satzstellung in den Psalmen, Diethelm Michel surveys the relationship between the imperfect consecutive (wayyiqtol) and the imperfect (yiqtol), specifically when the wayyiqtol follows the yiqtol. He begins his study with Ps 3:5 . The imperfects are highlighted in blue and the imperfects consecutive in red.
ק֭וֹלִי אֶל־יְהוָ֣ה אֶקְרָ֑א
וַיַּֽעֲנֵ֙נִי מֵהַ֖ר קָדְשׁ֣וֹ סֶֽלָה׃
I cried aloud to the Lord,
and he answered me from his holy hill. (ESV)
According to Michel, the wayyiqtol (“and he answered”) is used in the same way as when it follows the perfect (see my earlier post), namely to show a result. However, in this case, the psalmist is not looking back to an earlier fact as would be described by the perfect, but rather to something that occurred again and again. Thus, the imperfect is used with an iterative meaning. As such, a more appropriate translation might be:
Every time I would call to Yhwh,
he answered me from his holy mountain.
This allows us to maintain the distinction between the tenses while at the same time bring out the iterative sense of the imperfect. The answer was a consequence of the calling.
Michel points to two passages in Psalm 94. The first is found in vv. 5–7:
עַמְּךָ֣ יְהוָ֣ה יְדַכְּא֑וּ
אַ֭לְמָנָה וְגֵ֣ר יַהֲרֹ֑גוּ
וַ֭יֹּ֣אמְרוּ לֹ֣א יִרְאֶה־יָּ֑הּ
וְלֹא־יָ֜בִ֗ין אֱלֹהֵ֥י יַעֲקֹֽב׃
It is your people, Yhwh, that they crush!
It is your earth that they mistreat!
It is the widow and stranger that they kill!
It is orphans that they murder!
Thus, they say: “Yhwh cannot see,
the God of Jacob has no understanding.”
The imperfects again express iterative facts, as those under Yhwh’s special care continue to be victims of ill-treatment and murder. As a result, and expressed with the imperfect consecutive, the wrongdoer can say, “Yhwh cannot see.” The wayyiqtol gives the logical conclusion drawn by the one speaking. Later in the psalm, this relationship may not be quite as obvious (vv. 21–23).
יָ֭גוֹדּוּ עַל־נֶ֣פֶשׁ צַדִּ֑יק
וְדָ֖ם נָקִ֣י יַרְשִֽׁיעוּ׃
וַיְהִ֬י יְהוָ֣ה לִ֣י לְמִשְׂגָּ֑ב
וֵ֜אלֹהַ֗י לְצ֣וּר מַחְסִֽי׃
וַיָּ֤שֶׁב עֲלֵיהֶ֙ם׀ אֶת־אוֹנָ֗ם
יַ֜צְמִיתֵ֗ם יְהוָ֥ה אֱלֹהֵֽינוּ׃
They attack the life of a righteous one,
by condemning innocent blood.
Thus, Yhwh was to me a stronghold,
my God was to me a rock of refuge.
Thus, he repaid them their crime,
in their malice he wipes them out.
Yhwh our God wipes them out.
It is already clear form v. 17 that the deliverance has occurred for the psalmist; Yhwh was his help. Therefore, the distress of v. 21 is also gone. The imperfects of v. 21 denote preceding actions that were repeated [again an iterative sense of the imperfect]. V. 21 says that the enemies have attacked some righteousness in the psalmist, as Michel states, “some protégé of Yhwh.” As a result, since Yhwh is righteous, he must intervene, and the intervention of vv. 22, 23 is portrayed as the result of the actions in v. 21.
In conclusion, the relationship that exists between the imperfect and the imperfect consecutive is again one of cause-effect, just as in the case of perfect-imperfect consecutive. The only distinction is the way that the psalmist portrays the action of the cause. The perfect depicts a general, independent fact; the imperfect (most of the time) iterative action.
 Note how the ESV is translating the imperfect and imperfect consecutive the same way.
 Such distinction is also maintained by the NASB: “I was crying to the Lord …, and He answered me.”