Day Trading After-Market Lounge 1st June 2016, page-29

I certainly wouldnt be 'day trading' without live data.

For instance scalping, no chance on earth of doing this consistently with lagging data.

Buying momentum stocks with huge volume that are up on good news, well you couldnt do this without huge risk either

If you dont have live data you'd really need to do your homework before entering a trade, and you'd still be best to stick to short-term trading(or medium/long term trades) until you do

Just my 2 cents worth on the subject, all IMO