The most common trigger is an employee with several years of service asking for a long, planned absence: extended travel, study, a personal project, or recovery from sustained pressure at work. Many employers reserve sabbaticals as a retention tool for staff with three to five years of continuous service, and the agreement is what turns an informal "yes" into something both sides can rely on. A second scenario is the wellbeing break, where a business would rather grant proactive rest than lose a valued employee to burnout, and wants the terms recorded so the absence does not blur into open-ended sick leave.
Caring responsibilities make up a large share of requests too, where someone needs months away to look after a child, partner, or dependant but fully intends to come back. Here the right-to-return wording is the heart of the document, because the employee is taking a real financial risk and needs clarity on what they are returning to. The single most contested point in practice is whether the returning employee gets the exact same role or merely an equivalent one, and the agreement should resolve that before the leave starts, not after.
Two edge cases are worth flagging. If a request is really about a family-related entitlement, such as parental or unpaid leave covered by statutory rights, you should route it through the correct statutory mechanism rather than a sabbatical, because the legal protections differ sharply. And where an employer has informally granted breaks to several people over the years, that pattern can harden into an implied contractual right by custom and practice, so a one-off written agreement that states the break is discretionary protects the business from creating a precedent it never intended.