The value you need depends entirely on how long your network needs to transfer your file. Slow networks need longer timeouts. You can see how long your files are actually taking by watching About → Show log → Live → Profiling and looking at the Uploading and Downloading lines for size and time (more size → more time). Adding to the job the options --log-file and --log-file-log-level=Profiling will work too. Examples:
2018-11-28 08:22:42 -05 - [Profiling-Duplicati.Library.Main.BackendManager-UploadSpeed]: Uploaded 50.02 MB in 00:01:42.3183110, 500.63 KB/s
2018-11-26 15:57:53 -05 - [Profiling-Duplicati.Library.Main.BackendManager-DownloadSpeed]: Downloaded and decrypted 49.99 MB in 00:00:12.2495337, 4.08 MB/s
Upload speed is lower than download on many Internet connections. You can speed test your connection. Units may use multiples of bits (lowercase b), or bytes (uppercase B, where 1 byte = 8 bits). Division will give the theoretical minimum time, but other factors (such as CPU, disk, Duplicati, etc.) may slow things.
If you have set your job screen 5 Remote volume size larger than 50MB default, that will also take longer. Basically you want to leave enough time for your slowest transfer on slowest network with some margin…
Here are notes on --http-transfer-time, and OneDrive success using smaller volumes and larger timeouts.