Where it leaks
Slow progress claims. Variations not captured. Retentions un-tracked. Sub-contractor terms shorter than client terms. None of this is exotic — it's just rarely watched weekly.
What to fix first
Progress claim discipline. Issue claims on a schedule, not when someone gets around to it. Track the gap between work done and cash collected — it's usually bigger than you'd guess.
What changes
Cashflow stops being driven by completion dates and starts being driven by claim cycles. That's a different business.