It is very important as well to see same results from the Demo account and the Live account in the broker. Some brokers do not. They provide totally different quotes on both. There could be a change as well if the spread is different.
Also, if you are trading on live account, it is good to use the Historical data from the live server(even you see no huge difference in live and Demo).
More, keep in mind that some broker show different data on the different live servers. So if you collect data from one server, and then you open another live account(the broker might automatically open the account into another server) than you will need to collect data again if there is difference.