I did mine all at once
I guess we should call this the IFR ticket, but my last 2 cents is, I got mine over a 9 day period, start to finish. I found a USAir Captain who specializes in IFR training in your airplane. With the written passed, I took a week's vacation from work, got a cheap hotel and flew down to Beaufort, SC to train. We flew off the 40 hours of hood time over 8 days, so that's approx 6 hours/day. What a workout! All my takeoffs were under the hood, and the hood was only removed when we were below decision height and actually doing a landing. I think I looked out the window a total of 20 minutes over that 40 hours! Took the checkride the next day and passed. I have never been so dialed in to my flying skills as at the end of that 40 hours. What a high.
We even had my engine running rough on one of our jaunts, he had me keep the hood on and keep flying.
"Train the way you fly!" he would always say to me. In other words, I could have a rough engine in IMC, so I should get used to handling this under the hood. He believe in this mantra so much that he would not hand me charts in flight, or enter something in the Loran (12 years ago) for me. He kept reminding me that I fly single pilot IFR, so to act like he wasn't there.
As a result, my first IMC XC was a 3.0 hour trip to Memphis Intl. I couldn't find a layer that was not IMC, so I just hammered it out hand flying for 3 hours (no wing leveller) and ended the flight with an ILS at MEM. The concentrated training had significantly raised the bar on my stamina in the gages to where this flight felt like a walk in the park. Easy day didn't feel stressed or afraid, just on top of things.
This says nothing about my abilities, but I tell this tale because I believe that concentrated training in your own aircraft with the right instructor is a great way to go. IN the long run, you'll spend less $$ re-learning motor skills that got rusty between lessons, and you'll be spending so much time over the day with him/her that it offers full time learning.
To anyone in process with the IFR ticket I say, Welcome to another corner of the RV envelope! You can now really use your aircraft for travel. I'm always flexible in my plans, but waiting 6 hours for the skies to warm above icing temps or for Boomers to pass ususally gets it done. Don't forget that we GA guys can head towards our destination and if the Wx gets worse than forecast we can land at many more airports than the airlnes, wait it out and keep going.
Good stuff!
Art Treff