Estate agents: Big high street names vs solo/sole trader

I currently have a 1 bed flat for sale in a very trendy part of East London. Nice flat, nice street and excellent location. There is no tenants and the flat has been refreshed. Had 3 valuations and all came with similar strategy/asking price. I picked a solo agent with competitive rate but not a high street brand name. He has been great through the process however the flat went on the market on the 10th of Jan at the prices recommended and I only had 3 viewings.

Now, one of the other agent (big high street name) called me yesterday and told me the performance is poor and that she would expect 10 viewings a week at least if it was her as she would be calling people and get as many people through the door. Her all argument was that her calls to potential buyers and her database would get my flat sold.

As everybody I am a bit suspicious of estate agents selling you the dream and not performing. My view has always been that all buyers are online (on rightmove) and if they see something nice they would request a viewing. In the past I only bought and sold during sellers market but clearly things seems to be different.

Would it really make a difference to switch to a big high street recognised agency?