The perfect is merging with the simple past in American English.
Ex: He (had) worked in Saudi Arabia for several months.
... the issue of whether the past perfect tense is falling out of use ... .
The Usage Panel prefers the past perfect, but the simple past is often acceptable. Seventy-seven percent prefer had talked to talked in the sentence I asked if he had talked to his doctor. This leaves, of course, 23 percent for whom talked is unobjectionable. The panel is even more tolerant of the simple past in this example, which does not involve the reporting of discourse. In a sentence such as Before I was introduced to her, I heard/had heard the rumor about her, 59 percent would require had heard, while 41 percent would allow heard. Thus it seems likely that many readers will not notice the omission of had—that is, the use of the simple past in preference to the past perfect—in these situations.
Source § 68. verbs, tenses of. 1. Grammar. The American Heritage Book of English Usage. 1996