I've been meditating for 4 months now. Started off doing 10 minutes. Eventually worked my way up to doing one hour per day, with 2 or three sessions of one hour each on weekends or whenever spare time was available. Got a taste of the 1st jhana maybe 5-6 times but am struggling to get back to it. As of recently i've been losing motivation to practice, and I've been considering switching from samatha-focused TMI style to mahasi noting (which i've been doing in daily life occasionally). 

So my question is: should i focus strictly on developing concentration to the point where 1st jhana is consistent (i.e. i can get to 1st jhana in 90%+ of sessions) or should I start incorporating some vipassana without worrying too much about jhana?