If you use multiple devices, then you might have experienced waiting for sync to work.
In most cases, sync happens instantly when the Internet is working and the app's status says that SeriousMD is up to date.
The most likely scenario that happens when sync takes "a long time" to work is when the device is left sleeping for a long while (the screen is off, so iOS will conserve battery by disconnecting from Wifi, hence disconnecting SeriousMD). Thus, when you open the device and app again, it will take a bit of time to connect. Normally, it will take a few seconds to connect to wifi again, then 30 seconds for the SeriousMD Doctors app to try and sync.
So whatever data was added on that device, it won't sync until it connects. In the later releases, we have tweaked this to make it sync faster.
Another reason for slow sync is that the upload speed of the connection you are using has suddenly become slower OR the files are very large, especially the pictures. The more pictures, the more data that needs to be transmitted, hence longer the sync time.
However, we have already optimized images to be uploaded in the best possible size. It's now dependent on your Internet service provider.
The final reason is that your Wifi network is blocking the connection. This happens due to many reasons. For some hospitals, their wifi network can sometimes update filters or blocks to certain IP addresses so the app might not be able to connect because of it for a little while. For some network providers, be it a local connection or maybe if you are on mobile wifi, they sometimes block certain IP's. Just reboot your wifi device (router or pocket wifi device) and it should work properly.