I think either resistor set up can work, single or one for each LED. The single resistor would need to be adjusted if you changed the number of LEDs, you mentioned 8-10 if I'm following correctly. The single resistor would be at a higher power level, ~0.65 watts for the apparent 8 LED example you mention, just need to pick one with enough power rating, with some extra to be safe. The resistor(s) would be in series with the LEDs.

A more efficient option is to put the LEDs in a series-parallel combination. Say use 9 and put them in parallel groups of 3, then put those 3 groups in series. (or the other way, 3 series groups then in parallel, whichever wires easier in the model layout). That would get them up to 5.4V (1.8 x 3), with a single 10 ohm resistor in series needed. Then only about 0.036 watts would be dissipated/wasted by the resistor. Would lower the battery drain from about 0.18A to 0.06A for the 9 LEDs and the resistor.