Reading forums and interacting with other rpgers is can make for great food for thought. You don't have to agree with everyone or anyone. You don't have to take in what others say as something you absolutely must do. It is very thought provoking to see and hear what others are doing in their games though.
A lot, and I do mean a LOT, of people are sandboxers. These are folks who play in ongoing games that are made to be conducted in a series of scheduled sessions and provide a general game world as the basis and the DM has a variety of options for players to follow up on. This allows for more choice, options and randomness in general I think.
Then you have the "one-shots". These are game sessions in which a specific adventure will be played through, generally in one or two sessions and options are limited to what has been prepared for the specific adventure.
I don't think one is better than the other or one is more right or wrong than the other. What I do think is that the AD&D 1E core books and rules contained within them are geared more specifically to one-shot gaming. To be able to put up a game in a relatively short time and play it thorough in one or two sessions. This allows for "pick up" games to happen more readily, taking advantage of a few people who happen to find the time, interest and opportunity to play a game on short notice.
Having said that, one great Plus about the core books is that they include room for world creation and sandboxing. The writer (Gary Gygax) was a sandboxer of great notoriety. Thus, he made sure that outside of one-shots, he made sure the game could grow into something more than a published adventure module.
There is no doubt that beyond the one-shot game, the hard and fast "rules" become more akin to guidelines allowing the DM to personalize and give distinction to their gaming experience.
At home, I practically refuse to even consider running a one-shot game. Oh no, this is my world and I will explore every single inch of it the way my players and I best see fit. Oh yes, there will be house rules and custom made monsters and NPC's. There will be hand-waves of BtB specifics and whatever else it takes to bring my world to life.
On the other hand, I am considering going outside of my house to do some gaming, AD&D 1E of course. In that situation, there is no world yet. These are people I am only just or have yet to make their acquaintance. Because of that, I intend to stick very close to playing BtB.
This gives all of us new to each other a common ground to begin playing. We will most likely play one-shots to begin with, not knowing what kind of consistency we will be able to expect from the others in the group.
I hear and read of people playing games at conventions and special events and I know that these are referred to in the books themselves. All in all, it's the best way to get a group of strangers together to play the same game that another group of strangers is playing on the other side of the country or even in another country.
Speculating, I can see a group of us getting more familiar with each other and deciding that as a regular group that we want to cross that line of formality and establish a game world of our own, ending up somewhere between the one-shots and a full blown sandbox. Initially this might begin with making one house rule that we all agree on and drawing up a general gameworld and still using published modules and playing them as though they are places in our gameworld.
What a terrific, flexible and creative game AD&D is.