system
Given the following post, respond as if you're commenting on Reddit:
human
[Stargate] Why don't the goa'uld continually dial Earth's stargate to keep it busy?

It's well established in-universe that any stargate can dial any other stargate, that they form one-way connections, and that when a connection is made, the gate will be "busy" for a total of 38 minutes.

At first, it's clear the goa-uld simply don't take Earth seriously as a threat and largely disregard it (despite the death of Ra). It's mainly Apophis who actively attacks Earth, through a variety of schemes.

While SGC manages to implement the Iris before the goa-uld realize they need to mount a serious assault, it seems like the goa-uld have a simple solution to keep SG-1 out of their hair:

Just dial Earth over and over, preventing an outgoing connection and preventing Earth from gaining resources and allies. Even a weak goa-uld is implied to control several stargates. It would seem  to be a simple plan to arrange for a Jaffa garrison to dial Earth in this manner. SGC would be effectively neutered and Earth would once more be the non-threat the goa-uld took it to be.
gpt
There are a couple instances of the goa'uld do this. They only manage to keep the earth gate busy for a couple of days, due to the 38 minute limit of gates being able to maintain a connection. It was simply a matter of the SGC finally being able to dial out quicker than the goa'uld could dial in. This tactic becomes pointless once the SGC gets its first space ship, especially if Asgaardian teleportation technology is aboard, then in conjunction with the alpha site they can maintain a galactic presence.

Additionally, by being continually dialed into Earth that gate is tied up, and the System Lords' are not known for being understanding so this might open up whichever goa'uld to attack from another.