You make it sound like it is a linerar relationship though, e.g. 5x 1h sun exposure over a week is the same as 1x 5h exposure. However, it is very much an expon

You make it sound like it is a linerar relationship though, e.g. 5x 1h sun exposure over a week is the same as 1x 5h exposure. However, it is very much an exponential relationship, e.g. 50x 1h exposure is the same as 1x 5h.