It rather depends on A) the scan settings that you used, B) the system spec OS, CPU and RAM, C) the amount of data to be scanned and we have none of that information.

Seeing that one of the files being scanned in the image is an mp3 file, I don’t recall if mp3 files are scanned in a default Full System Scan. We don’t know if you chose to scan ALL files or the default selection or if you chose to scan archives or scan for PUPs. All of these would be likely to increase scan the duration.

I also see in your image that so far avast has scanned 113.4GB of data, which in itself is quite a lot, so what is the total amount of data on the system ?
Remember archive files are reported in windows by the archive compressed file size, but the avast scan extracts files from the archive (if you chose to scan archives). This would give a total greater than that reported by windows explorer.

Was there a particular reason to choose a Full System Scan ?