Nathaniel Sietz is an HR professional who built an entire People function from scratch as the only HR Manager at a logistics company that had no HR infrastructure. In this episode of Built by People Leaders, Nate introduces The 91st Day framework—a practical way to keep onboarding and culture-building going beyond the standard 90-day probation period. Ironically, that’s exactly when most companies stop investing in new hires, even though it’s also when many people decide to leave. He published the framework under the name Nate Hill.

Nate talks about the challenges People teams face as companies grow: onboarding that ends after the first week, managers who push back on structure because “things change too fast,” and acquisitions that create rumors and uncertainty, leading to preventable turnover. For companies that have outgrown informal communication and where leaders can’t keep track of everything themselves anymore, Nate explains how to replace ad hoc ways of working with simple, consistent people practices that scale.

• Onboarding that stops at day 90: Nate Hill explains how companies spend roughly $20,000 to hire one person, then withdraw cultural attention after probation—forcing repeat spend when new hires leave inside the three-month window.
• Trust erosion during acquisitions and rapid growth: Nate Hill describes employees updating resumes and crying in his office over layoff rumors, and how leadership distraction with new departments left the core team feeling left behind.
• Managers without an onboarding framework: Nate Hill addresses the gap where managers own onboarding but lack a structured plan, defaulting to one-week classroom orientations instead of month-long integration.

1. Co-design a month-long onboarding plan with each manager: Sit down with the hiring manager to build a role-specific 30-day timeline instead of using a generic company template. Secure manager buy-in so the plan is followed, not filed away.
2. Run 30-, 60-, and 90-day self-evaluations for employees and managers: Use these surveys to catch onboarding failures before the three-month attrition window. A downward trend signals it is time to rebuild that manager's onboarding plan.
3. Translate HR issues into leadership's own language: Reframe turnover, meeting time, and disengagement as financial cost for money-focused executives. Bring survey data and cost breakdowns as proof rather than subjective opinion.

• Why do new hires quit right after the probation period? Nate Hill explains that culture and manager attention often stop at day 90, so employees who impressed early feel forgotten once they are "safe." Most resignations happen around the three-month mark, which is why Nate Hill pushes companies to sustain support into the 91st day.
• How do you keep employees calm during an acquisition or rapid growth? Nate Hill recommends direct, top-down reassurance: he organized an all-hands meeting where the CEO personally told staff their jobs were safe, because rumors spread faster than management can contain them. Hearing it from the owner rebuilt trust that middle-layer messaging could not.
• How does HR earn trust with a skeptical executive team? Nate Hill positions HR as a partner, not a subordinate, and explicitly requests trust during interviews. He uses industry-specific analogies—like a surgeon showing up drunk to the OR as a "never do moment"—to make policy decisions land with leaders who don't think in HR terms.

Links & Resources Mentioned:

• Connect with Nate Hill on LinkedIn: https://www.linkedin.com/in/nathanielsietz/
• The 91st Day by Nate Hill — available on Kindle (Amazon) and hardcover (Barnes & Noble): www.the91stday.com