The phrase "preferably longer" is correct and can be used in written English.
You can use it when you want to express a preference for something being of greater length or duration than what is currently being discussed. For example: "We are looking for someone to take on the role of content writer, with a minimum of two years' experience, preferably longer."
Allow enough time for it to come to the correct temperature, at least 20 minutes but preferably longer.
Add the soy sauce and sesame oil, rub this mixture into the chicken and leave in the fridge to marinade for at least an hour, preferably longer.
"We are in negotiations with the ECB to try to win long-term guarantees for at least the next five years, preferably longer, but there are still gaps in the schedule and the bidding process is still going on.
This is generally done with patience and gravity, but Seal and Roden both suggest squeezing the flesh out in a sieve, rather than letting it drain for Ottolenghi's "hour at least, preferably longer", and I must say that, if done diligently, the results seem just as good.
Continue this practice for at least 30 days, preferably longer.
This's why AFC requires all mentors to commit to at least a year, preferably longer, with their mentee.
You should invest in stock markets for a minimum period of at least five or 10 years, and preferably much longer, to overcome the inevitable short-term volatility.
InSAR methods require at least a pair, (and preferably a longer time series), of SAR images to analyse the variation in phase.
Further development and testing of these conditions requires a large and more diverse sample than ours, and preferably a longer and/or more fluctuating time span.
The learning period should preferably be longer in any RI-type forecast modeling (e.g., Rundle et al., 2002, 2003; Tiampo et al., 2002; Holliday et al., 2005; Nanjo et al., 2006a, b, c).
It is, however, critical that the relationship is confirmed in an independent cohort of patients, preferably with longer follow-up time.
