Are some hacking timelines more advantageous than others?

No, nothing you mentioned has an effect on a portal.

• Minimum time between two portal hacks: 5 minutes
• Portal burn-out after 4 successful hacks
• Portal hackable again 4 hours after first successful hacking
• Only two things influence what items are dropped:
  • Own/enemy portal = more/less items
  • Portal level x => Items dropped with level x-2 to x+2

Example 1:

• Hack 1: 0:00h
• Hack 2: 0:05h
• Hack 3: 0:10h
• Hack 4: 0:15h
• Portal recovered at 4:00h

Example 2:

• Hack 1: 0:00h
• Hack 2: 3:45h
• Hack 3: 3:40h
• Hack 4: 3:55h
• Portal recovered at 4:00h

So if you have 15 (+ x) minutes, hack the portal 4 times and then leave, as there is nothing else to do for the next 4 hours.

Source: http://ingressfieldguide.com/content/faq