Phitsanulok's Walking Street is only held one night a week on Saturdays. At the end of the afternoon, the Sangkha Bucha Road becomes pedestrian and welcomes the stalls of vendors of all kinds. There are lots of clothing stands and you have to go at the end of the street near the river to find the part where most food stalls are, before they are very rare.
This is, from my point of view, not the most charming Walking Street in Thailand, but if you have never experienced the atmosphere of Walking Streets in Thailand, these night markets that only take place a few evenings per week (sometimes only one day per week like here), you definitely should go there.