i agree if youre not familliar with the lawn in question, mow trim blow. after you know what the mower can and cant reach you can trim first and mow the clippings. but 99% of the time i mow trim blow except when leaves start falling i might blow the leaves into the lawn and mulch them up.
Definitely in the spring for the first couple of cuts, Matt will start to trim first while I cut.
Once the growth slows down and there isn't as much trimming, we will cut first, then trim.
Also, if you are going to experience some lawns with an over-abundance of crabgrass growing all along the sidewalks, driveways etc., it is best to trim first, otherwise it will look kinda sloppy having the crabgrass shot all over the already cut lawn.
I don't think there is a right or wrong way. Just size up your lawns, and if the trimming is out of control, trim first. If not, then cut first, trim second.
I agree with 1Major on that. Crab grass or what ever if it is strewen on a cut lawn looks like crap. I don't think any one can actually answer your question though. It is one that you need to figure out yourself. alternate between the two untill you find out which is faster and looks the best. then stick with it. Heck I belive mowing is like this. the first few times i mow a new lawn I am looking for the fastest way to get it cut and look good. I use this way when I am trying to get caught up and Interupt my usual change direction routine.
TRIM - EDGE - MOW - BLOW - GO for the past 23 years.
If I wait to trim LAST, and I get hot or LAZY it won't get done! This way I knock out the hardest part, and then do the easy mowing. Save the best for last! Also keeps you from being so hot. Allows you to cool off on the mower.
Also as others have stated, allows you to mow and chop up any long trimmings and debris that you kick up when trimming.
This doesn't mean that I NEVER mow FIRST, just that trimming first makes mowing SO much easier.
Lots of leaves and debris lying on hardscapes i'll Trim, Blow, mow, blow. I blow before so all my trim clippings and leaves are on the turf. Then I'll mulch em up and blow again.
I'll Trim, Mow, Blow.
I always mow first, for the simple eason, that it saves time. When the trimming is done first, inevetibly, more trimming is going to get done than what is actually necessary. Generally, the trim length is equal to that of the mowing, anyway, so it's all the same. However, in extreme conditions, or just long conditions, many of times, the lawn is going to be double cut, anyway. So, what I do then, is again, mow first, then trim. What this does, is two things. First, it pulls all the long grass out freely into the area where it can be cut (already short where it lands). Second, it allows time for the grass that IS cut to dry, so essentially, it can be turned to dust. Now, to double cut is really not all that bad, since it takes MUCH less time to do it the second time, than the first. Mowing around trees isn't as meticulous, and you can sream across the lawn, and even so when doing the border.
Also, just a note: Whenever edging is done, it is ALWAYS done first. This way, much of the debris can be sucked up with the border pass, and then there is less trimming to do on the edges, since you are then only doing a topside.