I don't think that is a correct conclusion. It doesn't behave linearly.
"We can think of disease patterns as leaning deterministic or stochastic: In the former, an outbreak’s distribution is more linear and predictable; in the latter, randomness plays a much larger role and predictions are hard, if not impossible, to make. In deterministic trajectories, we expect what happened yesterday to give us a good sense of what to expect tomorrow. Stochastic phenomena, however, don’t operate like that—the same inputs don’t always produce the same outputs, and things can tip over quickly from one state to the other."
https://www.theatlantic.com/health/archive/2020/09/k-overloo...
Preventing these imperfections is extremely important in a very high infectivity environment like a hospital's Covid ward, but they don't really change the masks' impact on the epidemiologics of supermarket trips.
A protection level that only shifts the average time to infection of a Covid ward's staff from Monday to Thursday would be terrible, but the same level of protection added to otherwise unprotected supermarket goers can easily reduce the supermarkets' contribution to the R value from heavy to insignificant.
Yes, of you do not impeccably follow the procedures required by medical staff in high infectivity environments the small remaining risk of defense penetration will rise by a high factor, no, the remaining protection will still be much better than no mask.
"The virus can also spread after infected people sneeze, cough on, or touch surfaces, or objects, such as tables, doorknobs and handrails. Other people may become infected by touching these contaminated surfaces, then touching their eyes, noses or mouths without having cleaned their hands first."
https://www.who.int/emergencies/diseases/novel-coronavirus-2...
[1] https://www.worldometers.info/coronavirus/country/france/
The underestimating/overestimating is actually quite easy to understand: everybody thinks to themselves that a slightly reduced amount of countermeasures should be sufficient compared to the first wave, because it's less of an unknown now. And they might even be right about it! But the same process happens on multiple levels in parallel while everybody assumes all other remaining equal and then they compound. Relative to countermeasures in the first wave, governments weaken executive orders this time (by an amount that might be appropriate all other parameters being equal), regional administrations weaken their execution (by an amount that might be appropriate all other parameters being equal), private organizations, from corporations to knitting clubs weaken countermeasures in their procedures (by an amount that might be appropriate all other parameters being equal) and individual weaken both their personal protection habits and their adherence to all those rules, by an amount that might be appropriate all other parameters being equal.
Nobody can revert all those compounding weakenings, the only single point of correcting for them is at the top level: in the second wave, you need considerably stricter government rules to get the same effect. And even they are only corrected in a reactive way, when the numbers become too bad, when the wave becomes too high. Hence the almost universal big second waves.
Not all. At least here in Norway we had about double the confirmed infection rate on 12th November (771) that we had in the early peak on 26th March (423), 7 day averages. We are now down to 110 per 100 k people (14 day average).
But on the 9th March 17% of tests were positive, on the 18th of November it was 3.5%, now it is only 2.2%. But we test a lot more people now; 6k tests per day in the early peak in the spring, 31k in November, now about 90k per week, roughly 1600 per 100k people.
Here the second wave was regarded as rather serious but the threshold for regarding things as bad is rather lower than is usual in Europe; in comparison with most of our peers and neighbours we have it pretty good.
Sources: https://www.vg.no/spesial/2020/corona/#norge, https://www.vg.no/spesial/2020/corona/norden/
Based on that data, I can conclude that the measures do show some effect.
The effect is less observable in the "cases" data, where the daily number of cases indeed grew since 7th, but even there there should be a lag of a little less than a week from the point the measures start (it takes time for the people who were infected before measures to incubate and be able to be tested positive or get sick). Interestingly, that is what we see there: there was growth in 7-day average daily cases until Nov 13, then only on Nov 21 that number gets higher again. Which indeed points to the possibility of measures working less from that point on, but at least the growth since Nov 7 is also obviously lower than it was before, which is also what can be expected if the factor that the newer measures bring is low enough that the speed of the spread is reduced, but not high enough to reverse it.
So there are signs that the measures, as much as they are followed, have some effect, but sadly not enough to reverse the trend.
https://www.worldometers.info/coronavirus/country/lithuania/
Slovenia, on another side, has practically the same amount of daily cases for the last 30 days, when 7 day moving average is calculated, but the equvalent calculation of deaths show flattening only between 17th and 26th, and then there's growth of daily deaths again. As the average number of daily deaths is the statistics which is less influenced by the number of tests performed and it's independent on the success of contact tracing, that shows that in Slovenia the spread is still not under control, and additionally, that the month long flattening of the daily cases could mean that there's a bottleneck in health system -- that relatively fixed number of persons could be processed daily, but that due to the priorities those who are processed are, through the time, the patients with worse conditions, resulting in continuous growth of deaths (and the last is just a hypothesis which can be verified or rejected based on the exact related information from Slovenia).