Case file LinkedIn Crossclimb #777: 4-letter ladder, 5 middle exhibits, combo prompt "A compound word for a flow of air directly behind a boat or plane that increases it speed.". Endpoints: WIND (top) and TAIL (bottom).
Middle phase answers: "Easier ____ than done" = SAID; "Button pressed after writing an email" = SEND; "Proceed slowly by an indirect route, or the newest word game on LinkedIn" = WEND; "It might come back with you after a trip to the beach" = SAND; "Large piece of fabric used to propel a boat" = SAIL.
Ordering phase: the valid middle chain is WEND → SEND → SAND → SAID → SAIL. This permutation is the only valid one-letter chain for these answers.
Evidence link: WIND → WEND. I→E at the second letter (WIND → WEND).
Evidence link: WEND → SEND. W→S at the first letter (WEND → SEND).
Evidence link: SEND → SAND. E→A at the second letter (SEND → SAND).
Evidence link: SAND → SAID. N→I at the third letter (SAND → SAID).
Evidence link: SAID → SAIL. D→L at the fourth letter (SAID → SAIL).
Evidence link: SAIL → TAIL. S→T at the first letter (SAIL → TAIL).
Verdict: WIND → WEND → SEND → SAND → SAID → SAIL → TAIL satisfies every one-letter constraint. The combo clue "A compound word for a flow of air directly behind a boat or plane that increases it speed." describes both end words together — "WIND" and "TAIL" each differ by one letter from their adjacent middle rungs and satisfy the shared top+bottom prompt.