If you had the tooth removed and the root of the tooth was not in the
sinus (no perforation) and it had adequate length and there was no
issue if thin bone or damaged bone due to extraction then you could
have had the implant placed that day.
Now if you did not make up your mind yet implant or bridge then
obviously no implant placement. However ideally a decision was needed
at that visit and you were not ready to make it, hence a compromise may
have occured.

Otherwise the socket should have been grafted and the implant placed
after the graft heals.
if your #5 had very short roots, then you would need the sinus lift.
You could have had the graft done during extraction and then more
grafting during the sinus lift.

If during the extraction bone around the tooth was comprimised or it
has compromised due to gum disease (periodontitis) then I could
understand waiting for the graft to heal prior to implant placement.

Your dentist may be more conservative and that may explain the separate
procedures or like you were told maybe the panorex machine was not
available or maybe a consult with the oral surgeon was necessary and
for some reason that was not done yet.

Ken if you are having these questions you are not done discussing your
treatment options. You need to understand better the "why" and the "why
not the other way". I am not aware of the details of your case and
perhaps there are very good reasons why things are being done this way,
but in order to make the right decisions you need to understand those
reasons clear enough so that you can explain them to others. I do need
see that yet from your posts.
Remember statisticaly patients remember 50% of what is told to them
from the consultation. There is just too much information and it can
get overwelming.
The last thing I want you to do is to say that you are getting advice
from a newsgroup but if our conversation raised some questions in your
mind you need to have those answered so that you are in control of your
treatment.