The only time you have to place an order is the only time the supplier is closed

Anyone working chairside has a day made of back-to-back appointments. Real breaks are few and almost always fall when everyone else's offices are shut.

The result is a situation that repeats itself: you notice something is missing at eight in the evening, as you lock up, and at that hour there is nothing you can do.

The next morning you are back chairside at nine, and the right moment to make the call never arrives. So the order slips, and slips again.

The cost of that slippage is not theoretical. It is the box that runs out mid-week, the appointment reorganised, the product replaced by a stopgap you had at the back of the cupboard.

It is also the emergency reorder at a worse price, because when you need it by tomorrow you are no longer choosing a supplier, you are choosing whoever delivers first.

The point is that the traditional purchasing process is synchronous: it requires two people to be available at the same moment. And those two people have hours that are incompatible by design.

An online catalogue breaks that dependency. The order gets placed at seven in the morning, at lunchtime, on a Sunday evening, and it does not require anyone to be awake at the other end.

This also changes which purchases you make. Things that require a phone call tend to be postponed until they become urgent; things that take two minutes get done when they occur to you.

It is why, on a marketplace, routine reordering tends to be more regular and less concentrated in emergencies.

The same holds for the tedious part: comparing two products, checking a technical sheet, looking at a seller's shipping terms. All things you can do calmly at eleven at night and would never do at eleven in the morning.

It does not solve everything, of course. If the product is not in the catalogue you cannot buy it at any hour, and delivery still depends on the courier's timescales.

But it removes the most banal and most underestimated obstacle, namely that the only time you have is the only time you cannot use it.

In summary: the chairside day leaves gaps only outside office hours, the traditional process is synchronous and needs two people at once, slippage produces stock-outs and emergency reorders on worse terms, an online catalogue makes purchasing asynchronous, and purchases that take two minutes get done while those needing a phone call get postponed.