What are you doing to test ISP leased line speeds?

I have multiple providers using Metro-E circuits. I would like some suggestions to test the line speed periodically either automatic or less manual.

Here's how I'm doing it now. I transfer a 500MB/1GB file from my desktop (at the data center) to a workstations C: at a remote site. I expect a lot of overhead but given the lines 100Mbit bi-directional speed I'd be satisfied with 80/80 Mbit.

I then record the date/workstations used/and file size/speed results in an Excel spreadsheet. This is very manual and time consuming, probably not that accurate. I do sometimes check link utilization if the speed is questionable.

Are remote sites utilize on average 10% of the link, but sometimes users notice a slow speed if they need to transfer files.

Troubleshooting link speed with an ISP it's usually their "policers" that are configured incorrectly.

Since we experience issues with our services I try to be proactive instead of reactive to a complaint. Anyone out here have a better method to check link speed periodically? No downtime can be incurred so cannot run direct connections between hardware.

Thanks for your suggestions.