Around here it's not at all uncommon to have areas with spotty 3G coverage. Sometimes it's enough to maintain phone connectivity but not enough for data; sometimes even normal telephony becomes unavailable.
Switching to GSM helps, but even then sometimes reception drops to zero. It usually rebounds as soon as you move a few metres away from the dead zone, but it's enough to momentarily disconnect the data link.

This wouldn't be much of a problem if it wasn't that the data connection doesn't come back up instantly when the link does; I set automatic connection on the GPRS network and set the search interval to 5 minutes, which is the shortest available, but that's still too long. Can it be somehow shortened to 1 minute or so? I'm ok with tinkering with configuration files via terminal.

well, odd to say I'd like to check the connection less often than 60 min, basically the same question of yours...

I discovered that setting an interval for connection check makes the device check and really connect (if the flag is set to "connect automatically every connection"). In absence of wlan (or disable), it will connect to gprs every x mins, using auto-disconnect disconnects after x mins, so you have auto email checker!

Maybe that was known, anyway searching the forum long ago found a thread with people saying you could not auto check emails on N900