Are you using cotton batting or polyester?
If it's polyester, spray basting won't do a lot of good.
It might help a little on a small project like a table runner, but I've never had much success on larger projects.
the spray baste doesn't stick to poly like it will to cotton.
sooooo ... i always find that i need to baste much closer together if i want to straight-line quilt using poly batting.
as in no more than 2" apart.
of course, the problem might be me. you never know. LOL
regardless of the batting type, i recommend you get the open toe accufoot for quilting.
you can more easily see where you're going.
between the "walking foot" function and minute adjustments to needle position, you can lay your stitches down just about anywhere you want to between the toes.
i even prefer the open toe foot for stitching in or near the ditch.
as for the project you've shown us in this thread ...
the alternating "waves" on the back might not be what you wanted, but they do add an interesting texture to the back. the fact that you wisely chose to alternate the direction in which you stitched makes them look even more interesting.
look upon them as a serendipitous design change and decide to love them.
