Meeting people in person changes the working relationship measurably and the change lasts. Whether it is worth the airfare depends on the size of the engagement, and the threshold is lower than most clients assume.
What actually changes
Written messages read differently once you have met somebody. Ambiguity is interpreted generously rather than anxiously. People raise problems earlier. And you stop being an entity that sends work and becomes a person, which affects how much discretionary effort arrives.
Nobody can put a figure on this and every client who has done it reports it.
What to do while you are there
Work alongside them for two days. Sit at a desk in the same room, do your own work, and answer questions as they arise. It is the single most useful use of the time and it is nothing like a meeting.
Have a one-to-one with each person, away from the floor, and ask the two questions from the entry on feedback: what would make your job easier, and what am I doing that wastes your time. In person, and after two days of sitting together, you will get real answers.
Meet the on-site supervisor properly, and meet whoever runs the operation. Both relationships pay for themselves the first time something goes wrong.
Have a meal with the team. It is ordinary and it is not optional.
What not to do
Arrive unannounced. It produces no better information and starts the visit as an inspection.
Spend the trip in meetings with management. You can do that from home.
Promise anything. A visit generates goodwill and goodwill generates promises, and a promise made in a room in Cebu that cannot be delivered from Sydney costs more than the visit was worth.
Frequency
Annually is enough for most engagements. Twice in the first year is better if the team is being built, once every two years is thin for a team of any size.
The most valuable visit is the second one, because the first is inevitably partly a tour.
The reverse trip
Bringing somebody to you is expensive, requires a visa, and is disproportionately effective. A person who has seen your office, met your customers and understood what the work is for returns with context no briefing supplies, and they tell everybody else.
Where the budget allows one trip in either direction, this is frequently the better one. It is also a substantial recognition and it is understood as such.
The one-person engagement
Hard to justify on cost and often still right, particularly for the isolation reasons the previous entry describes. A person who has met their client once behaves differently towards the work for years afterwards.
If a trip is genuinely out of reach, the substitutes are a video call with cameras on rather than a chat message, and enough contact that they know what you look like.
Practicalities
Cebu has an international airport with direct connections from several Asian hubs and from Australia. Dumaguete generally requires a domestic connection.
Tell the provider well ahead. Space has to be arranged, and the team should know you are coming rather than discovering it on the morning.
What it costs
Flights, several nights, and about a week including travel. Against the cost of one avoidable resignation it is not a close comparison for any team above two or three people.