What he said. But I just decide on an individual basis rather than a single rule.
Do I want to hold expectation of feedback over her head? A Roma might not give a shit. Can even go backwards and Sergei could blacklist you. Can I be bothered? Phone bookings are more convenient but a system booking at least has a 'paper trail' in case she 'forgets'. Do I want her to read my feedback? Possibly if she's a fussy cow (I have good feedback). Would I rather she didn't have my phone number on her computer? Possibly, but she'll need the number anyway to 'apologise' for keeping me waiting or having an 'emergency'.
Some prossie bookings offer ("prefer/insist") on phone bookings, some on text, some on email, some backed up by system bookings and some not. Depends on how the wind blows in one ear and out of the other. Check her 'preferences': pointless trying to get a cat to think like a dog.