So after spending many years worrying about being able to attract girls, I finally have got my game to the level where I have the opposite problem - being able to put in enough time to maintain my girlfriend and give her enough attention.

Thought I would share a few thoughts on how I try to manage it, and keen to hear anyone elses thoughts.
1) Keep your promises and manage expectations: The first thing to note is that if you are time poor, it is very important for you to manage your girlfriends expectations about when she can expect attention and when she cannot. Make sure if you have a period of challenging hours at work that you let her know well ahead of time, to get used to the idea that you will be less available. Related to this - make sure when you do promise to give her attention / be available, that you keep those promises. This is very important for establishing credibility and for getting her to respect those other times when you aren't available
2) Put in 'blocks' of time: If you are trying to work, but also fielding messages from your girlfriend or talking to her then the result will be that you don't get any work done and she feels neglected. This is lose / lose. Work hard for an hour, then spend an hour focused on nothing but her. This will give you a much better outcome than wasting 2 hours trying to manage both.
3) Manage online / phone interaction: Related to the above, what can you do if your girlfriend is constantly messaging you, hitting you up on facebook etc. For messages, I use an app that you can set when you are busy that auto replies to her and buys you some time (it's called 'Girlfriend SMS'). The other thing is if you are busy, don't open her facebook messages until you are ready to reply to them - nothing sends a girl into a spin faster than seeing "read" on a facebook PM with no reply.

Hope this helps. Keen to hear any other tips anyone has on managing their girlfriend whilst busy then please comment, would like to hear it.

You have some good ideas, but there are some fundamental flaws.

1) Your first point, I completely agree with. You want to have credibility, be a man of your word. However, don't get into the vicious cycle of overplanning and her expecting attention. You'll become predictable and boring. As a guy, this makes perfect logical sense to us, but kills attraction over time. Make your plans, stick to your word, but as a hard working guy you have priorities outside her.

2)"Blocks" of time? See "predictable and boring". I'm not sure what sort of job you have, but whatever the job may be work time is time for WORK. Not texting, calling, social media, what have you. You're showing a weak passion for your career, you're compromising something that was previously important to you for something new. A bad quality. Talking to friends/family/girlfriends while "on the clock" is for emergencies only - if it's really that important, they can call you on a "work phone". Speaking of which, if you have a job that isn't "on the clock" then start treating it like one. In a sense I agree with what you're trying to say, but you're only half-assing it. 50/50? How about 100% work when you're working, then 100% girlfriend when you're with her?

3)I get what you're saying, but it all sounds so... lame. Matter of fact, let me just conclude..

First off, Rookie, you've got one total post count here. Nobody's going to take a topic like this seriously until you have hundreds if not thousands - the post count is the only concrete way to show experience with PUA forums (in addition to account status such as moderator).

Second, it sounds like you're still in this "must please the woman" mode. "Nothing sends a girl into a spin faster than seeing a ready with no reply message". Why is this a bad thing? If she's interested, shes asking questions to herself like "why didn't he reply? was it something I said? was he too busy? am I coming off too boring or clingy?" just like every other AFC on these forums. So now she's thinking about you even more... again, how is this a bad thing? Granted, sometimes you may feel that if you don't reply immediately, you feel like you're indecisive or neglecting her, but I almost guarantee that's just your incorrect perception. Reply immediately to communication when you have time and they are interesting communications. It sounds like you have a very REACTIVE approach to dating, rather than an ACTIVE one. Reply to messages when YOU want to! You're in this trap of thinking that pleasing her right now, giving her what she wants right now, it going to work in the long run. I'd be willing to bet that these women are just testing you to see if you're a challenge, and you're making SOME effort with what you've conveyed here... but SOME is not enough.