I found a site that gives 41 as the number of instruments required to make a “small” orchestra. It also gave sizes for larger orchestras. In each size, there’s always at least two oboes.
What if you wanted to start an orchestra, but couldn’t find any oboists?
How about other required instruments?
Don’t play music with which you need a lot of oboes.
The orchestra for “classical music”…i.e., Mozart, Haydn…usually goes like this:
Woodwinds in twos: flutes, oboes, clarinets, bassoons.
Brass: four F horns, two trumpets, two trombones.
The “usual complement” of strings: 8-10 first violins, 8-10 second violins, 6-8 violas, 6-8 cellos, 4-6 double basses.
Some guy standing in the back doing whatever’s necessary for percussion. Most often timpani.
Once you get into the Romantic period, things open up a bit. Added woodwind players, several doubling on other things…piccolo, English horn, bass clarinet, contrabassoon. Added horns, extra trumpets and trombones, and the tuba appears. LOTS more percussion. Strings augmented to match the added power of the winds.