Fridge temperatures need to be checked and recorded twice per day - or look at it as once per shift.
Regular temperature checks help catch any issues early before they become food safety problems. If you spot temperatures rising above 5°C, you'll need to monitor it more closely.
If you are a venue that opens in the morning then it's good practice to carry out a fridge temperature check in the morning. Presumably you will also be open in the afternoon too so make sure to carry out a second fridge temperature check in the afternoon as well. This will mean that you are carrying out the required two checks per day.
If you are open in the evening, you won't need to carry out a third check during this shift because you have already carried out the two checks on each unit each day.
Most people choose to number their fridges (for example fridge 1, fridge 2 etc) but you can use any system that makes sense for you. For example you could use a lettering system (fridge a, fridge b) or you could use names for the fridges if that is how your team recognize them (milk fridge etc).
Ultimately the only thing that matters is having a system which is robust, repeatable and makes sense for you.