Yes, they build up, they give shivers (the killer must be watching you) and Felix's new advantage will add up as well. If you take care of yourself with that configuration, it will take 18.5 seconds, you should heal and work on generations to get more resiliency value and then heal yourself once the killer is close. I would also recommend using a kit because you'll get 50% efficiency in one and you'll be able to heal in 9.2 seconds, you can also use your kit to cure everyone and, once it's over, you can continue taking care of yourself. Self-care is meta+ very useful because only one person is needed to complete an action and without it you need two.
So in terms of healing, what does this mean? Returning to personal care, let's look at some scenarios, but they can also apply to medicine cabinets and other forms of healing. Take Claudette Morel to levels 1, 2 and 3, respectively, to unlock level I, II and III botanical knowledge for all other characters.
Suppose you have knowledge of botany (+ 33%) and resilience (+ 9%), but you are devastated (-20%) and you are taking care of yourself (-50%).The potential of self-taught people is the +50% bonus on skill tests. The problem is that you start with a -35% progression in skill tests.
Every accumulation you earn by passing a skill test adds a 15% bonus to skill checks. After doing enough skill tests, you can almost cure someone instantly. Desperate measures add up to 14% for every injured survivor, 2 injured survivors plus personal care and botanical knowledge 3% in 18 seconds. Desperate measures, botanical knowledge, resilience and chills increase Self Care's healing speed.
Botanical knowledge helps mitigate this at a more reasonable time, and if you manage to keep control of your team's healing while using botanical knowledge, you'll save everyone a good amount of time, since your healings will take approximately 15 seconds longer than others.