I am learning the 14 position system of the G Melodic Minor. The way I have been practicing it is play all 14 positions for 5 minutes total. Then play the scale on each string ascending and descending for maybe 2 minutes each string. Is that effective enough? Any other ways to practice it?

Hi. Pebber has lots of videos on youtube concerning various ways to practice and memorize scales. This should get you started.

I would recommend making Daily tuplet runs through Segovia's Diatonic Major and Melodic Minor Scales book. Every single scale, every single day till you can do any of them in your sleep.

Oh and btw TS/ The reason I recommended the Segovian forms of Major/Mel Minor are bc/ 1.)they never force you to play "out of position", 2.) They only involve 6 or 7 (unless I am mistaken there are 6) scale paths + the unique one for F-Major, 3.) each one gives you 2-3 Octaves of bang for your buck and 3.) I found them immensely helpful in purge purging many of my technical issues w/ their consectutive string shifts. and 4.) Segovia was THE man, and is worth emulating in every way possible.

One of the best ways is to write them out.....this is how...
Write out each pattern 10 times before moving to the next pattern.
This is much better than writing all the patterns at the same time.
What you do is concentrate on one at a time and that really helps.
Plus..
Play each 10 times and move to the next.
14 positions isnt all that much.....this is the best way to explain the definition.....Melodic Minor.