Hendon told BBC Radio Kent: "We didn't have a good start last season, and that (match fitness) could have been a part of it.
"We're believers you get fitness in matches so we've put lots of games in."
He added: "We've changed things round a bit, plenty of games, but not all the players will play in every game."
"Not only that, a lot of the clubs we are playing games against are local clubs, they all want friendlies and it is a bit of revenue for them as well, so we're putting a bit back in as well."
The League Two club have three friendlies at home. Millwall come to Priestfield on 23 July, Leyton Orient are the opponents three days later and Championship new boys Peterborough face the Gills on 30 July.
The club will also send the first team squad to Bromley, Dartford, Weymouth, Welling United , Braintree Town, Faversham Town and Ebbsfleet United.
They will also field a side in friendlies at Erith & Belvedere, Ramsgate and Tonbridge Angels.
Their first game of the league two season is at home to Cheltenham on Saturday 6 August.
Hendon added talk of AFC Wimbledon captain Danny Kedwell joining Gillingham is premature, although the club would be interested in signing the striker.
Hendon added: "Personally I've watched the lad a few times as part of my job, I watch a lot of games, he's a good hard-working centre forward and can score goals.
"If they've accepted his request and he is available I am sure he could be of interest to us."
Source: BBC Sport
Source: BBC Sport