Fewer than you own, almost certainly. Most people accumulate a collection rather than building one, and end up with six bottles of which they wear two.
The honest answer is two or three
Not because more is extravagant, but because more than three stops getting worn. A fourth and fifth bottle sit in the cupboard while you reach for the same two, and every additional one makes the choice slower without making it better.
Two works for most people. Three is comfortable. Beyond that you are collecting rather than wearing, which is a legitimate hobby and a different activity.
The roles worth filling
The everyday one. Close, quiet, holds all day without demanding attention. This gets more wear than everything else combined, and it is the hardest to choose because nothing about it is impressive in a shop.
The cold one. Denser and warmer, for the months when a light composition barely registers. In a climate like this one it is not optional.
The occasional one. Heavier, more distinctive, worn rarely enough to stay interesting. Buy this last. It is the most tempting first and the least used.
Why more stops working
There is a practical reason beyond storage. An opened bottle is at its best for two to three years. Own five and you will not finish any of them inside that window, so you are permanently wearing fragrance slightly past its best.
Own two, in 30 ml, and you will get through them while they are still what you bought.
Rotation matters more than range
Wearing one fragrance every day means your nose adapts to it within a few weeks and you stop perceiving it. The usual response is to apply more, which does not fix it and does mean everyone else is getting considerably more than they were.
Two in rotation prevents that entirely, and each one is more enjoyable on the day you come back to it. This is a better argument for a second bottle than variety is.
What to do with the ones you do not wear
Work out why before buying anything else, because the reason will repeat.
Too sweet by the afternoon. Too loud for a room with other people in it. Bought on a first impression that did not survive hour four. Given as a gift and never right on your skin.
Those patterns are more useful than any list of notes you think you like, and naming them rules out more than any preference does.
When a third is worth it
A third bottle earns its place if it genuinely does something the other two do not.
A heavier evening fragrance when the other two are both daytime. A light summer one when both of the others have weight. Those are real gaps.
Another variation on something you already own is not, however much you like it. Two similar fragrances mean one of them is not being worn, and it is usually the more expensive one, kept for occasions that do not arrive.
Sizes
For a two or three bottle collection, 30 ml is almost always the right size. You will finish it inside the two to three years an opened bottle stays at its best, and the per millilitre saving on the larger bottle is not a saving if the last third has gone flat.
The exception is the everyday fragrance, if you have settled on one and worn it long enough to be sure. That is the only bottle most people actually finish.
Where to start if you are starting
One at a time, and the everyday one first. It will get several times the wear of anything else and it deserves the longest decision.
Samples rather than bottles for that decision. A Discovery Box holds five 1.5 ml samples, one of each fragrance HOUSE OF ZIGGIMAY makes, which is enough to wear each properly for a day and find the one you keep reaching for.