Yeah methadone is fine to take whenever, and it will also keep you feeling well and actually high, whereas suboxone will just prevent you from withdrawing when you're deeply into strong opiate addiction.
The reason suboxone causes precipitated withdrawal is because it is a partial agonist, so it doesn't fully substitute for full agonists like heroin, morphine, fent, oxy, etc. And it has an incredible strong affinity for the receptor, so it will outcompete all other opioids. So what happens is, it instantly kicks all of the other opioids out of the receptor when it gets into your system, and if you're dependent on full agonists, that causes you to immediately go into full withdrawal. Methadone, on the other hand, not only doesn't kick other opioids out, it is a very strong full agonist itself. So there is no risk of precipitated withdrawal, and it will fully substitute for any other opioid. The result is that you can feel good the very first time you take it.
In fact methadone is very pleasurable, it's probably my favorite recreational opioid. It's very strong, gets me really nicely high, and lasts a very long time so you're not constantly in a cycle of being high and then feeling like shit. It's got horrific withdrawals that last a very long time, but it is much easier to taper over a long period of time, so in that sense it can be easier to get off than fent or heroin. The main advantage is that it keeps you stable, you get it legally and don't end up spending all your money on it, or worrying about overdosing. It allows you to get back to living a stable life.