Less mass conscription?

Well, to be specific it depends on when and where. This is one of those things that has changed A LOT over the centuries. And varies significantly from country to country.

I will describe the process during the middle ages in England and France somewhat as that is my area of expertise.

Someone else will have to jump in and expand on this to cover other places and other time periods.

After the Norman conquest of England in 1066, England was a feudal monarchy ruled ostensibly by a monarch but with a lot of the administrative tasks being entrusted to the Barons, that is nobles that held land in fief for the King.

By law, every Baron, indeed all of the landed nobility, was responsible for maintaining a certain amount of military force that could be called upon by the king in times of need.

These people were sometimes armored knights and armsmen, but were more often peasant levies armed with spears and bows. The task of making these various lords levies in to an effective fighting force would fall either to the King or one of his senior nobles.

For example, at the Battle of Agincourt in 1415 Edward of Norwich, 2nd Duke of York, commanded the vanguard of the English forces.

Now these armies were raised and paid for by the crown of England and it's nobility, which gathered their money from taxes paid. Usually taxes on goods produced, and sometimes on trade.

Where it gets interesting is the fact that France to much the same thing, but they had, for various reasons, far less effective peasant levies. But they WERE able to field more armored knights, especially on their home turf.

So, because the armored knights were typically either heavy infantry or cavalry, and the peasant levies were typically spears or bows, the French wound up with a lot more heavy horse and a lot fewer archers than the English.

The solution: Hire mercenaries from Italy that specialized in Crossbows.

The problem: Sworn armsmen and peasant levies were typically more loyal, and far cheaper than mercenaries.

During the medieval period then, armies were raised typically by royal decree from noblemen who owed fealty to their crown via knights, armsmen and peasant levies. The armies were typically made up of infantry and cavalry which were divided in to various types of units depending on where and when we are talking about.

And all of these can then be supplemented by the hiring of, usually foreign, mercenaries for an additional cost.