Submitting a new paper just after another was accepted by the same journal

With one paper every two years I don’t think you will be seen as gaming the system.

Go ahead and submit.

If your submissions to the journal are being accepted, there is nothing wrong with submitting more papers to the journal: It means that your submissions are up to the standard of the journal, and you should feel free to submit further papers to that journal at the rate at which you can produce content of that quality.

It would be different if your submissions keep being rejected at that journal. In that case, you should reconsider whether your work is suitable for that venue, and if you submit to the journal at a too high rate, this might well annoy the editors.

As to which rate of submissions is acceptable (in case they are rejected), this is highly dependent on the field and journal, so it is hard to give a conclusive number. (In my field, one rejected a paper every two years even in a top journal wouldn't be seen as an issue by most people.)