Its a little hard to say without knowing how experienced you are: "cutting/designing FURIOUSLY on things that the director did not want in the first place" - are you sure it isn't your priorities that are wasting time? I only ask as I have met people who talk about all the abstract design they love & want to do, but when I ask them about cutting basic stuff (eg ambiences with correct perspective cutting, cutting basic FX for M&E coverage, cutting vehicle effects etc) they aren't very interested.
You can effectively divide the required material for a film soundtrack into either real or subjective. Real sounds are the essential 'real' coverage - every scene needs ambiences, real sound effects, doors, vehicles etc... The only ways to go wrong with them is due to taste, lack of experience, limited resources etc. Does the door sound effect you just cut seem real & normal? Fine, move on...
Subjective is more interpretive, and if you do not have any clear direction (from the director) whatsoever then unless your taste & the directors intentions are magically the same, then it is likely you will waste your time. When time & budget are scarce this is not the best way to work, and you need to have direction ie be briefed, even if its only a ten minute phone conversation or an email of timecoded questions.
One aspect to consider, and I have struck this before, the senior person at the company may be the one who wants to retain the primary relationship with the director. They may not want you contacting the director discussing things without them in the loop. If they dont have time to sit in on a spotting session, or to be contacting the director, then make a short list of what you NEED to know, with timecode & scene #s, and send it to your supervisor. Ask them if either you can send it to the director or can they send it. If they want to retain control they will send it, if not & you can send it directly (& cc them) then you have a direct line of communication.
Randy Thom said it once & it is incredibly good advice: (i'm not quoting verbatim) it is cheap to experiment at the start of a project, and it gets more expensive as deadlines approach. So if you are going to go down blind alleys etc, better to do it at the start, & show a rough mix (even just for a scene or moment) to the director & get their feedback, than to do what you describe of putting lots of work into something they don't want.
Also remember: low budget films are often made by first timer directors. They may not know what they want until they hear it. They may not have the language or experience to describe it. But they will know it when they hear it - even hearing the wrong thing can make them clarify what they think the right thing is. Directors like to direct. Give them something to direct! & early!