Unit charges and costs in Plait work as follows: a booking can have one unit cost / charge per person.  If more than one could potentially apply then the one of the highest value is selected.

This can lead to some misunderstandings, especially around overnight visits starting on Friday or Sunday or visits starting or finishing on a bank holiday.  Our examples will focus on the implications for visits around the weekend, but it is easy to see how the logic transfers to visits that overlap with a bank holiday.

If you had the simplest realistic Tariffs period setup:

and you set up some unit charges as shown below:

which you applied to the tariffs matrix as follows:

then a week of nights would have four bookings charged at £175 and three at £200.  This is because a Fri/Sat booking is eligible for the £175 unit rate (for the Friday part) and the £200 rate (for the Saturday part), but only the highest rate is chosen.  The Sat/Sun event only attracts the £200 unit rate.  The Sun/Mon event again attracts two unit rates - £200 for the Sunday part, and £175 for the part that falls on Monday morning, but only the highest rate is chosen.

For those of you who think on Friday afternoon that "the weekend starts here" then this is probably what you want.  

However, people who want to ensure that only two overnights per week attract the weekend rate (an entirely defensible view, since there are two days in a weekend - at least since the early 20th Century) need to do some extra work and add some lines to the tariff period setup.  If the two overnights that attract weekend rates should be Fri/Sat and Sat/Sun then you can use something like this:

alternatively, the setup to have the enhcaned rate apply for Sat/Sun and Sun/Mon would be along the lines of:

In these last two cases you would have the following rows in your tariffs matrix:

If there is a chance of hourly paid or charged work running overnight, then you will also need rows in the tariffs matrix to make sure that the hour we have put in to attract the unit rate also attract the relevant hourly rates.