A large share of professional connection happens outside working hours. The timing is treated as neutral and is not, because obligations at those hours are unevenly distributed.
Informal contact does formal work
Assignments, referrals and introductions circulate through conversation among people who know each other, and much of that conversation happens after the workday ends.
An employee absent from those settings is not being excluded from anything official. She is simply not present when the informal allocation happens, and the effect on her work is the same.
Over several years the difference shows up as a smaller network, fewer inbound opportunities and a thinner set of colleagues who can speak about her work from personal experience.
Evening obligations are not distributed evenly
Childcare, eldercare and household coverage fall disproportionately on women in American households, and those responsibilities are concentrated in exactly the hours networking uses.
Costs compound: attending an evening event may require paid care, which converts a professional opportunity into an expense that colleagues without dependents do not face.
The same applies to conference travel, where an overnight absence requires arranging coverage that a colleague can simply not arrange.
Venue choice narrows attendance further
Events built around drinking exclude people who do not drink for religious, health or personal reasons, and they raise safety considerations that fall unequally on junior women.
Golf outings and similar activities assume prior participation in a sport with its own cost and access history, which functions as a second filter layered on the first.
The alternatives are known and undersubscribed
Structured connection during working hours — scheduled coffee, internal mentoring programs, cross-team project rotations — reaches everyone on the payroll by design.
Such programs are often dismissed as artificial compared with organic relationships, but the organic version is also structured, just by a schedule nobody voted on.
Individual responses have limits
An employee can build relationships in daytime one-to-one meetings, which works and takes more of her time than a single event takes a colleague.
She can also ask that key discussions be summarized in writing afterward, which is a reasonable request and makes the informal allocation visible to people who were not there.
Neither substitutes for an employer moving the events themselves, which is the only change that alters who is in the room rather than how the absent compensate.