Many of us travel from A to B via C. Those of us that live in the catchment area for provincial airports probably spend most of their time going from A to B via C. The system works well; all your flights are on one booking and on one ticket and if, for any reason, you miss a connection you are placed on the next flight. If that involves an overnight stay, irritating though that may be, the airline will (in Europe, anyway) find you somewhere to stay - or, at least, make sure that some arrangements are made for you to be looked after.
There are rules which have to be followed with regard to how your journey is made up. These affect how the tickets are issued (the flights must all be on the same ticket) and the flights must also all be on the same booking. Sometimes, even when the flights are on a separate ticket and booking, if they are with the same legacy - (that is "traditional") airline, then they will make arrangements for you, should you miss a connection.
So far, so good. Until the travel techy types got hold of the flight connection notion, thought about low cost airlines, mixed in a smidgin of marketing bloke (or blokess) and came up with the idea of "self connect". What a wizard wheeze! Great! Where do I get my award! .... The idea was that you can now mix a low cost carriers (LCC's) with a legacy airline (or other LCC's) and you had this fancy title of "self connect" which was supposed to give the concept an idea of credibility.
Okay. Stop right there.
The traditional version of the connecting flight is enshrined in the IATA regulations and in Europe, backed up with stuff from the EU. It is an accepted principle by all legacy airlines and most importantly, works. The marketing-and-techy inspired "self connect" system is enshrined in nothing at all. So, whereas on those websites that suggest self connect and little box does come up (if you click it!), I am going to read the riot act with regard to what you are letting yourself in for.
Self connect has nothing to do with anything connecting with anything. These are totally separate, individual flights. There is no continuity at all - indeed, the use of the word "connect" is wholly misleading. A better term would be "The Dead Risky Option". You are travelling on a wing and a prayer.
The critical thing is that with any of these self connect arrangements, you have to fly from airport one to airport two. Land. Collect your bags (if you have any) go through security and walk out into the arrivals hall. You then have to go over to the departures area, check in again, go through security and board your second flight. Don't even think of asking where the transfer lounge is situated.
The above is, of course, pointed out in a box on those websites that offer this sort of connection. The issue is that, by even providing that box, the concept appears to attract an air of normality - as if it is some sort of accepted standard practice (which, of course, it isn't!)
The actual time you need to allow for the connection is a matter of conjecture. If a connection is booked with the same legacy to legacy (so called "inline") airline or offline (that is, one legacy airline to another legacy airline) then the connection is protected under the "Minimum Connecting Time" (MCT) rules. As long as the correct time is allowed, if a connection is missed, then it is the responsibility of the delivering airline to sort you out. (There is a side-issue, here of interlining but for the moment, we will set that aside).
The MCT rules do not apply with self-connect. If the first flight is late - tough. If it is cancelled - tough, if you didn't allow long enough or spilt some tea on your shirt and had to change and so, arrived late for check-in - tough. It is this message that people need to grasp - that no matter what, you are booking two totally different and separate travel "events" and it is your responsibility and yours alone to make flight number 2 in the allotted time. Do not expect any mercy from any of the airlines involved. The whole self connect "thing" is based on a "No prisoners taken, no quarter given" premise.
I am not saying you should never use "self connect" type arrangements. If they work, they work but if they don't and you miss flight number 2, you have only one option - buy another ticket. And, if it is last minute and you are at the airport, then chances are, you are going to have to pay an awful lot more money than the cost of the flight however-many-days-ago it was, when you first bought the flights.
You have now been warned!