I haven't done a great deal, but have had a few bowling machine sessions.
Something to think about for those last few indoor nets... these are all about establishing your rhythm - for a batsman and a bowler. For a batsman, it doesn't matter if you don't middle everything (or anything really), what matters is that you are happy with your technique and getting into good positions to play the ball. Is your head still, is that allowing your feet to move, this is what will get you early season runs. If you are smashing the ball to all parts in the indoor nets, the slow tennis ball bounce outside could cause you no end of grief...
For a bowler it is important that you have loosened up your bowling action and have a generated a reliable repeatable action. Most importantly you know what length you want to bowl - early season pitches need bowling on a much fuller length to test dodgy pitches and uncertain batting techniques. If you have been bowling it half way down all winter get used to watching the ball sail over square leg for 6 on the slow spring pitches...
bring on April 18th...