For what it's worth...The author of Luke's revisions/omissions are suggestive of his understanding of Mark and Matt.
First, the author of Luke clearly did not interpret Mark or Matt's expression of "tribulation" as referring to events thousands of years in the future. He revised his sources to say : There will be great distress in the land and wrath against this people. His understanding would not seem strange if it were not for the Adventist spin we are familiar with. Clearly, he understood the "tribulation" of Mark and "great tribulation" of Matt as referring to the Roman suppression of Jewish rebellion in Jerusalem.
Notably, he dropped entirely the lines that follow (Matt 24:21b,22) that said the days would be 'shortened' on account of 'the elect' (Christian Jews) as this clearly did no longer fit his time of writing, a generation later.
Another alteration he made was removing the "immediately after the tribulation of those days..." in Matt (24:29). Instead, he dropped the line entirely.
He also adds a new intertextual typology from Tobit not found in his sources Mark or Matt. He introduces a delay, an 'appointed time' needing to be fulfilled before the restoration. In Tobit the writer uses those words for the period between the return to Jerusalem and the rebuilding of the Temple, which was decades long. Rather than see it as a weakness of faith he saw it as providential. The writer of Luke, it seems, saw a parallel in his day. Living decades after 70 he saw the Jerusalem largely resume as a city but the Temple still in ruins as well, but more importantly no Son of Man.
Luke also adds (21:27,28) the line that 'when you see the Son of Man coming, know your deliverance is near'. This is not in Mark or Matt. He seems at pains to temporally distance the Jerusalem events from the deliverance here again. He has introduced a delay "appointed time" and erased words that suggested the two were very near in time. Here he temporally links the Son of Man's coming with imminent deliverance.
Especially interesting is his seeming omission of Matts 24:10-12, 14. This is likely because his copy of Matt did not yet have those lines. They also speak to a later generation of Christians whose disappointment had made them grow cold. It also ends with the anachronistic prediction of the Gospel being preached in the whole world. These lines are almost certainly a later gloss, as they would have been useful for Luke if he had seen it, given his agenda of explaining the delay.
I guess that's enough for now.