Time controls were beginning to be used in the mid 1800's, with clocks becoming a regular appearance starting in 1861.
The very first tournament where the double-sided chess clock was used was London 1883, which set a minimum limit of 15 moves per hour, failure to do so resulting in forfeit of the game by the player who has exceeded the limit. The games started at noon and the playing session would continue to 5pm, after which–should the game not yet be concluded–there was a two hour interval for supper followed by the adjournment (until 11pm, if necessary).
Source: Kevin Spraggett
Additionally, he mentions how there was no standard time control until later, when 40 in 2.5 hours, followed by 16 or 20 in an hour became commonplace.
While preventing players from thinking too long over individual moves was one of the reasons for the introduction of time controls, adjournments were also a consideration.
As @Saibot mentioned in a comment, deciding on a new time control isn't easy. Also mentioned in Spraggett's blog, players are reluctant to change the current time controls.