I used to take 9 hours to complete writing (scoring, analyzing, etc) a 20 page psychological evaluation.

I divided it into 9 sections - and definitely eating the frog was part of it (doing the parts I disliked the most first).

I also made a list of the FASTEST average times for each section.

I DID use a timer, but didn't stick to it rigidly.

Here's how it worked out:

1. Start with the FROG section, which say, I know I can do, if I don't procrastinate, in 30 minutes. I set the timer for 30 minutes. I know it may take longer (or miraculously, may get done sooner) so I'm not taking the timer "literally" - what it does is it lets me know if I stay focused, I will most likely get it done soon, which motivates me to keep going.

Find what works for you - but I will say, these time saving hacks are wonderful!