I think at the end of the day, you just never know because of statistics of the day or hour or ride. Your should always just sign in when your window opens and do 60 +max for SDD and then work backwards as +3 might bring better luck than +4 or 5.
When we made our FP+ last Sunday per our post above, it was just me doing the FP+ ressies, and we got greedy and wasted time for that matter. We did the following in sequence at 7AM last Sunday:
First tried SDD +1 (nothing)
then tried SDD +2 - nothing
then tried SDD +3 - got 6PM slot
Then tried FOP +1 - nothing
Then tried FOP +2 - made a mistake and wasted some time
Tried FOP +2 again and got a 10:00AMish....
Tried 7DMT at 60 and got 6PM
Had no problems with the rest....
Some points to conclude here:
1) We wasted some time trying SDD + less than max, and FOP with less than next max
2) We wasted some time with mistakes
3) It was only me (DH) making FP+ - I don't know the answer to this, but if more than one person works in close contact (both you and another making FP+ at same time), you might get better results...