Pretty much what Noxid said:
Yes, if you want a bright, bold print, you will want to flash it, then hit it again.
Really, the only way to keep it from clogging once it hits 90 degrees farenheit is to keep working. Like ZERO breaks. You have to keep the ink moving and the stencil loaded. And you need to print AGGRESSIVELY. Meaning you need to hit it hard to keep clogs cleared.
A little off contact with the high opacity WB inks goes a long way too. I use a bit of off contact with any WB ink. If you are printing correctly, the screen will snap off the garment, much like plastisol (especially with high opacity WB inks) and help keep the mesh clearer.
If you DO get a clog, you can stop and spray the screen with some water, or glass cleaner and rub both sides of the screen. Make sure to wipe the shirt side of the screen off of any smudges and make sure to test on a scrap before resuming production.
Biggest thing is not panicking. If you get a clog that you can't clear by a hard stroke, stay calm, handle it, move on. If you freak out, everything spirals out of control. Something that you need to train yourself to do, especially if you're used to printing with plastisol.
Tips to avoid clogs? Well, I have a thermometer in the shop and I don't really need to look at it when the temps in the shop hit 90. I can tell instantly by how the ink is behaving and it starts to "gel up" a bit. If I only have a couple more tees or hoodies to do, I'll keep going. If I have loads more to do, then I'll just shut down for the day. Because, being stubborn only ruins tees and hoodies! Point being: Try to get an earlier start and get done before it hits 90 degrees.
Plan your day accordingly. If you are printing a number of different screens, start the day with the ones that might clog the easiest - halftones, higher mesh, certain ink colors like white and/or yellow.
Plan out your mesh counts. While I prefer using 180's on most everything, sometimes it makes more sense to use say...a 158 on something that has tight and curly fonts (for example) and avoid permanent clogs.
Yes, you can get permanent clogs. Or clogs that "build up" over time. Or rather, clogs that can be so cloggy that you need to blast them out with a power washer ON. So with that said...
Make sure if you are using the screen over and over again, that you are using a stencil hardener. As stencil failure when/if it happens, WILL happen in the washout booth. EVEN with "water based safe emulsion". EVEN with stencil hardeners if the screen sees hundreds of prints and wash outs.
Always good to have a back up screen ready. Or at least some screens that can be coated and dried quickly.