3. Selector boxes only give you what's in the box
This sounds obvious, but is very important for selector boxes.
A selector box gives you the thing in the box - It doesn't give you anything else.
If a selector box gives you an operative, you won't automatically get anything else for that operative, including their 4* event weapon and their logistics set.
Without their 4* event weapon and their logistics set, the operative will probably not be that good, so you will need to factor in the time and Presence/stamina needed to get them.
Most players will usually [/hopefully] do the most efficient thing and spend most of their Presence/stamina on the current event to pull logistics officers from the event store.
This is the most efficient way of getting logistics officers and event weapons, and hence is what you should be doing in order to get perfect logistics officers for your operatives.
If the operative you get from a selector box isn't part of the current event, then you'll have to get their logistics officer and 4* weapon from the respective Operations.
(Mind Refinement, and Arms Hub, respectively)
This is less efficient than getting their logistics officers and event weapons from the event store.
If you spend your Presence/stamina on the selector box operative, then you may not get as many logistics officers and event weapons as you want from the current event if you use your stamina for Operations instead.
As such, an operative selector box can sound great, but you may not have the investment to immediately make good use of the operative you get out of it.
You should therefore generally pick an operative who will be useful to you in the long run, not what you immediately need for the current event or a specific piece of content.