It does take time to sign players. One disadvantage this summer is that the people now in charge have not been there to identify targets and try to build relationships with agents and clubs, in advance.
If you really want Player X then it helps where possible to have put some ground work in, weeks if not months earlier.
That said, if we've been trying to sign say, Luiz and it's more or less "Nah, not sure, come back in a few weeks" from his camp then there does come a time where you just have to stop calling and move on.
I would think that such time is already upon us if not fast approaching. Leave loans till late, but we cannot make our need for value on the one hand and to make a hard sell on the other, jeopardise the work that has to be done to improve the squad as a whole.
It's a delicate judgement call but they are experienced professionals and I expect them to alter course when needed. If they take other parties bona fides as genuine then they wait a little more, judge case by case, keeping other irons in the fire.
We have to see the results of that within the next fortnight.