I'm doing Eat to Perform, and before that just tracked macros/flexible dieted, which I think is basically IIFYM, although I don't call it that. For me pre-ETP it was easiest just to use the TDEE method (where you include the average workout calories for the week upfront rather than eating different amounts when you worked out) and a custom goal. Since workout calories were already included in my goal I logged exercise as one calorie.

Now with ETP I am eating less on rest days, but how I do that is log a standard 500 calories (the difference between a rest day and others) when I work out and then add 125 to my carbs in my head on those days (I note my intended macros in my notes: they are 125 g protein, 60 g fat, and 100/225 g carbs, depending on whether it's a workout day). Anyway, you probably don't need to know that unless you prefer/find it easier to log exercise.

(I also try to mostly eat mostly nutrient dense foods, but I also like fitting in some ice cream or chocolate and focusing on the overall diet and trying different things like, with ETP, how white rice works as a post WO meal or some such.)

I do iifym, open diary, I'm currently doing a 12 week cut my maintnence cals are ~2600. I'm cutting at 2200 rest days 200/90/130, 2400 gym days 275/80/130. Loosing about .5#/wk. I also sometimes do an even higher carb day about once every two weeks which leaves me wicked hungry but helps weight to drop. I like the Nicole c article ....but. ..getting as close to tour macros everyday as she suggests doesn't seem necessary. Also are you in the eat train progress group the have a bunch of good articles about what iifym is and what it isn't.