As already mentioned, the time between re-evaluations depends on how likely you are deemed to recover enough to go off disability. Upon initial approval, this is determined by your past history and current situation, and could later change again if your condition worsens or vice versa.

Read SSA - POMS: DI 28001.020 - Frequency of Continuing Disability Reviews (CDRs) - 08/09/2023 for the most detailed response to your question.

When I applied for SSDI I had 10 psych hospitalizations and 12 IOPs within the 3 1/2 years that preceded it. My condition had worsened, greatly, over that period. In between, I had attempted to return to work several times, most attempts lasting short periods and only reaching part-time. Only once did I reach full-time again for a while, which was followed by my worst of the bad episodes, including ECT.

Initially on SSDI, I received CDRs more frequently. My condition was still very bad. There are "short form CDRs" and "long form CDRs". The latter requires more details and generally comes less frequently. They ask questions like if you've returned to work/school or how likely that might be, in your doctor's opinion. More detailed questions relate to what you are able to do most days (capabilities for Activities of Daily Living).

As Nammu wrote, if deemed a very long-term (or permanent) disability, the reviews are years between each other. As also mentioned, they'll ask for updates on any new mental healthcare providers and the frequency that you usually see them.

Though not relevant to most people here, know that an American collecting SSDI (or SS retirement) can continue receiving it if they move abroad (with a few exception countries...maybe Iran, Russia, Syria, or the like). This is not the case for SSI. In the former cases, this is arranged through a designated American embassy in (or near) the foreign country. There are other steps, too. Also, if a review requiring a doctor is needed, there are designed "approved" local doctors for that.