Is a hold in lieu of a procedure turn specifically one hold on an RNAV approach? I was looking at RNAV (GPS) RWY 6. I considered that conceivably ATC could have me enter the hold at an altitude requiring a rapid descent to get to the initial approach altitude.

I know that unless NoPT is specified on the initial segment or from the TAA sector that you must do at least 1 hold, but what I wasn't sure was could you do more than one hold at your own discretion?

So, say, you were told to cross the IAF at 4000 and you felt like losing 2000 feet in half a hold would make your passengers uncomfortable, could you just make two laps?  Would you have to ask ATC for permission first?

It looks like crossing the hold fix is your initial approach fix and then it's subsequently an intermediate fix so it seems like the design is that you enter the hold and then cross the holding fix on your way into the approach, so it seems like it's designated that you cross the fix only twice, but I wanted to be sure.

Edit:

Certainly there are exceptions.  When directed by ATC to fly a straight in approach, the hold-in-lieu is not required.  If NoPT is designated for your TAA region or on your initial segment, then it is forbidden.

To rephrase my question, given that your hold-in-lieu is required then your lower bound is 1 hold.  Is there a designated upper bound of 1 hold as well?

I.e., if a hold -in-lieu-of-procedure turn is required, is it 1 and only 1 hold?

Sorry for the confusion.
When flying a hold-in-leiu-of-procedure-turn and the exemptions from that procedure are not met, you must fly that procedure exactly once. From the AIM, 5-4-9(a)(5):


  The  holding  pattern  distance  or  time
  specified in the profile view must be observed. For a
  hold−in−lieu−of−PT,  the  holding  pattern  direction
  must  be  flown  as  depicted  and  the  specified  leg
  length/timing  must  not  be  exceeded.  Maximum
  holding  airspeed  limitations  as  set  forth  for  all
  holding 
  patterns apply. 
  The holding pattern maneuver is completed when the aircraft is established on the inbound course after executing the appropriate entry. If cleared for the approach prior to returning to the holding  fix,  and  the  aircraft  is  at  the  prescribed altitude, additional circuits of the holding pattern are
  not necessary nor expected by ATC. If pilots elect to make additional circuits to lose excessive altitude or to  become  better  established  on  course,  it  is  their responsibility to so advise ATC upon receipt of their
  approach clearance.


Further notes: I'm not sure quite what you mean by losing 2000 feet in "half a hold", but if you got a clearance to maintain 4000 until established, you could start your descent immediately after crossing ODAZO, giving you 8 miles plus a one-minute turn to descend. At 120 kt, that's 4 minutes for the 8 miles, so 5 minutes for 2,000 feet or 400 ft/min - perfectly reasonable.

Finally, you mention that "When directed by ATC to fly a straight in approach, the hold-in-lieu is not required." Your statement should be stronger: as when NoPT is printed on the chart, a straight-in clearance forbids the procedure turn/HILOPT unless you ask for and receive approval from ATC.