Depends on your personal situation I think...your overall exposure and the potential severity of outcome if you caught the virus.
If you are shielding, older than 80, have an underlying health condition or are particularly unfit then it could be seen as an effective barrier because in that case it’s one of very few routes to catching the virus.
I think for others who are out and about working or who catching coronavirus isn’t as statistically high a risk of complication I wouldn’t bother. Personally, I’ve only been in lockdown because it’s mandated for the greater good. If it was just about me, I’m not that bothered about catching it and would just use hand washing/not touching my face as the main barrier against a most likely outcome of a week feeling a bit poorly.