Film, television, comics, books and games all have the opportunity to be presented either as a singular one-shot release, or as a series of episodes released (ideally) at regular time intervals. Both models have value, and knowing what the value is can help you choose which release type is best for your material.
One-shot releases are, by definition, singular events. This requires positioning them as such with your audience. The big-budget, blockbuster way is with media saturation: publicity tours, advertising and promotions galore. Copromotional tie-in transmedia also needs to be positioned around the event so that the whole package creates a big moment that the audience wants to participate in -- because it's here today, but gone tomorrow(ish).
On a smaller scale, it still requires building buzz, within the budget you have to work with. Social media is a part of that, but it is still rare to end up cash positive with a media release that's supported by social media alone. Publicity tours / event appearances, and whatever broader media exposure you can finagle, will still be part of promoting a successful release.
Since the singular event is momentary by nature, the ramp-up of audience interest must happen over a short time period. This requires a concentrated expenditure of money and effort.
Most feature films are one-shots, and certainly all independent features need to be thought of as such. But even serialized features like the Marvel Universe movies are promoted like one-shots since their release cycle is so long (audiences attention drifts after six months or a year). That concentrated publicity effort is necessary because people simply have other things to think about unless you pique their interest during your release window.
Episodic content must also compete in a crowded field for audience attention, but the shorter release cycles (daily, weekly, monthly) afford more of an opportunity to slowly build an audience (provided you've got the funding to keep producing while you climb the slope). By having new content on a regular basis, short-cycle episodic releases also have less audience attention drift than annual or biannual event releases (never mind true one-shots).
Television and comics have been making use of episodic releases for most of their history, to great effect. With smaller budgets (and smaller audiences) comic and TV franchises become a part of the culture through ongoing effort rather than singular, memorable events.
For indie producers, the lower cost, greater effort outlay is often more feasible than creating a singular event. And while it used to be that broadcast and cable channels had a monopoly on short-cycle episodic filmed narrative, the advent of channels like YouTube and Vimeo has made it possible for independents to release episodic content to a potentially large audience.
On the gaming side, Telltale pioneered successful episodic game releasing. Thanks to direct distribution channels like Steam, it is now possible for other developers to follow suit without fighting retailers' shelf policies and restocking cycles (something no indie developer has the clout to do).
Building an audience slowly through continual effort is often the most effective way for someone without deep pockets to achieve widespread success and reach a substantial audience.
But in order to be successful with episodic, a producer needs stamina. Slow-build episodic releasing is best suited to teams with a "slow and steady wins the race" production mentality, and a commitment to hitting the cyclical target even if quality sometimes suffers.
Television and comics have prioritized regularity for decades. Producers always attempt to put out the absolute best content possible, but in the end it's the regularity that matters most. Of course, this can result in continually declining quality and loss of audience -- but that's the discipline of episodic. You have to let go of bad ideas quickly, so you can focus on making the next episode great. (And you have to trust your audience is also willing to let go of continuity when you fix mistakes.) Episodic is like a marathon: sometimes you let go of your measure of success on one mile just to make it to the next one.
One-shots are best for producers who work best when sprinting. While one shot projects can take a long time to create (feature animation, for example), the bulk of the work effort is still concentrated in principal production (with pre and post production spikes, if you're doing it right), and the publicity effort is also a blitz. It's more like four sprints than a marathon. And the slow build needed to gather a meaningful audience requires multiple sprints, rather than a constant but measured pace of work.
In considering episodic versus one-shot, you need to consider your budgets, stability (you can't keep most kinds of episodic series going if talent and locations are transient), and personality (many people can do both, and if you're one of those it comes down to your attitude about the particular project). Doing this analysis will help you choose a release format that's right for you and your project.