Influxdb schema design for large amounts of fast data, multiple or single database?

Question

We are using influxdb at different industrial sites, where we log up to 10.000 values ranging from 1Hz to 1000Hz sample rate, from 3-5 different machines - resulting in something like 1GB data/hour. The logging is handles by simple HTTP line-protocal calls to an Influxdb 1.8 server. Running on a xeon 2.5Ghz 10c 64Gb ram 6TB SSD raid 5 array.

Right now the values are stored in the same database with a measurement for each machine, with a retention policy of 20weeks with a shard duration of 1week.

The data is visualized through grafana mostly.

Many people query the database at once through multiple grafana dashboards - which can tend to be fairly slow when I retrieve large amounts of data. No cross measurement calculations are performed, it is only visual plots.

Will I get any read-speed benefits from doing multiple databases instead of a single database with multiple measurements?

When getting data from a database, do influx need to "open" files containing data from all measurements in order to find data from a specific measurement?