The most valuable thing a software team can do is ship. Users care about functionality, about experience, not about your SDLC, your agile rituals, or your naming conventions.
SDLC exists because collaboration needs structure, and structure is overhead even when necessary. Every round of the cycle takes time. Write, review, test, merge, deploy. SDLC slows you down by definition.
A healthy ratio is 80% real work, 20% overhead from the SDLC. I have seen it inverted. Developers stuck in the procedure, not the product. Five times the capex for the same result, and developer time is already the biggest line item in most companies. That is the spend, but the real cost is the release you never made.